This is interesting. Enlarging being a generally solitary pursuit, you tend to arrive at your habits and preferences in a vacuum and sometimes you wonder how your own techniques match those of others who are working away in their own darkrooms. I especially relate to the comments on manipulation. In that 15-25 second range, my burns and dodges feel smooth and natural, at 60 secs they feel clumsy and unsure, I have to count along with my audible to know how much of a burn I'm giving and can hopefully repeat it.
That is called grain. It is supposed to be there.
Most come in between 24 to 36 seconds with 24 being optimum for a base exposure. I make the exposure in 3's; 3, 6, 9 12, 15 etc. Anything longer than 36 seonds seems to take forever.The same for the burns and dodges, increments of 3. For me manipulations at less than a 24 second base seem to be erratic and more noticable.
Seems I watched too much TV as a kid as well. I max my base exposures between 16-20 seconds f11 with a V54 cold light and prefer short burn times, 6-7 seconds. I have a programable timer which helps immensely.