Yes: fixed time -- most of the time.

2 minutes using D-72 1+2. 3 minutes when using Ansco 113 (Amidol) developer.

Film is done until you get the desired contrast index. Paper is done "to
completion." But that is not quite true: if you leave the paper in the
developer for an hour or so (I have not tried this), it will turn black
even if the safelights are off; You gotta be reasonable. But once paper is
developped "enough" it will only get darker by developping longer. I
sometimes do that if I slightly underexposed a sheet, but if I am off by
much, that is not good enough, and I just make another.

They probably do, but my temperatures do not vary much because my
temperature control valve supplies controlled water to the print washer,
and that overflows into my washing sink that, in turn, overflows into my
processing sink. If either of those sinks gets too deep, the water
overflows down the drain. Normally it is the processing sink that does that.

There's a technique called printing for first black. What it amounts to
is finding based upon your "standard negative" a printing exposure time
and development time that yield the first area along the clear portion of
your negative whereby a visible separation is no longer apparent.
Typically that might be "for grade 2 about 18 seconds of exposure and
about 2 minutes of development in dektol at 68F" The idea being that you
will have a full range of tones "5 stops" which the paper will still hold
and achieve the 18 second exposure and two minute development.

Each paper you will learn is somewhat different, Resin Coated papers can
develop quite fast and have the nick name of "rapid contrast" fast
development and fast exposure with more narrow tonal range.

I seem to recall that More info about printing for first black can be
found in books like the Darkroom Cookbook/Steve Anchell and various
photo darkroom centered books.

Personally I always tailor my development times per the paper and
negatives printing , sometimes I extend the development time or shorten
it to 1 minute, never less than a minute, seldom more than three...
mostly 2 minutes. Most of my negatives print very well at two minutes
and I would rather change the exposure slightly and adjust the filters
to keep the development time relatively constant.

Paper is developed to completion, no more no less.
It's important not to use too short a time (46 sec.
seems a bit short; I would develop RC paper a minimum
1 minute and probably 90 secs. If you develop longer
you will simply increase the apparent contrast but
not real contrast (i.e., the paper curve as a whole
moves but overall density is not increased.) My times w
ould be minimum 90 seconds for RC and 2 minutes for
fiber in dektol 1:2; usually I develop 2&1/2 minutes
with fiber. This is merely to ensure full development
in _fresh_ developer.

Any variations have more to do with (1) developer
dilution (since dektol can be diluted up to 1:8 and
still produce acceptable results) and developer
exhaustion. Greater dilution requires a longer time
until completion. But even at a standard dilution
the more prints you process the longer you will need
to develop in a given tray of print developer (i.e,
the developer simply loses strength and activity.
The Factor Method as described in Adams' book The
Print can help you determine the additional length
of development time needed as print developer gets
used up in order to develop to completion.

Since it is difficult to control all the variables--temp and developer
freshness--I'd recommend starting with looking for the first emergence of
any image.  Then leave in the developer 5-6 times that # of seconds.  As an
example, when I use MG IV RC for work prints, I usually see the first
emergency of an image at 10 sec, so my dev time is 60 sec.  As the developer
tends to chill a bit or get a bit worked, the emergence time may drift a
bit.

When I switch to FB for final prints of the same MG IV, I often find the
emergence time is more like 30-40 sec.  Consequently, the time in the
developer is usually about 3+ minutes.

This method has worked for me, and a couple of test prints will probably
help you find what you feel is a "complete" development given the momentary
condition of the developer.  This 5-6 times the emergence time seems to work
well.

I am a hobbyist and don't usually have time to do countless prints at a
given session before I dump my chemicals.  If you are printing larger
numbers of images, I'd watch the emergence time (if it is getting longer and
longer) AND the numbers of prints recommended as the max on the label, I'd
start from scratch  mixing new developer.

Good luck,  Sam

Almost always, because paper is developed to finality. Film is not.

While it is usually stated that prints are developed to
"completion" rather than to a specified contrast in fact to some extent
development can be used to compensate for exposure. The contrast is not
variable over much of a range if full blacks are to be obtained but
some papers allow perhaps a half grade from development time change.
Also, some papers, particularly warm tone papers, change image tone a
little with variation in development time. Warmer for shorter times,
cooler with longer times.
At some point extending development will begin to increase fog
more rapidly than the image.
The time needed to develop full black wtih normal exposure depends
somewhat on the emulsion and developer. Warm tone papers generally are
developed for longer than neutral or cold toned ones. Active
developers, like Dektol, develop more rapidly than less active ones
like Selectol Soft.
Most modern RC papers contain a layer of developer under the
emulsion. This is to permit their use in rapid access "activation"
processors but it also affects the development time in standard
developers. These papers show an image quickly, perhaps 15 seconds, and
develop fully in 60 to 90 seconds. There is little variation possible
in development. Papers without incorporated developer show the first
image more slowly, typically at around 30 seconds and usually take from
2 to 3 minutes to develop fully. The instructions for the paper will
usually give a recommended time.  Too short a time will give blotchy
blacks or light blacks despite increased exposure, overly long
development, more than about 5 minutes, may generate fog or poor blacks
despite the long development. My target time for fiber and
non-developer-incorporated RC papers is around 2 minutes, for developer
incorporated papers around 75 seconds.
I've found that judging print appearance during development to be
difficult so I generally developed for a fixed time and decide if the
print got the right exposure or is the right value of contrast in white
light after the print is fixed. Many papers change appearance when dry
so that is another complication.
"Development to completion" is simply development until the blacks
are at or near the maximum density the material is capable of.  Film
OTOH, is usually developed to a specified value of contrast. The
exposure may be adjusted to keep the maximum density at a certain
value, but it will most often be well below the maximum value the film
is capable of.
--
Richard Knoppow
Los Angeles, CA, USA
dickburk@ix.netcom.com