Having known some obsessive people years back who literally spent a year photographing gray cards and checking results with a densitometer, and thinking out the theory, (spinning gives more agitation to the outside as it moves further in one revolution), it can be quite over thought and drawn out. The linear speed is the radius times the rotational rate, but more simply the horse on the outside of the track has a longer race.
Straight up and down should give more agitation to the center of the frame, in theory.
It is probably impossible in any normal tank system to get "perfect" agitation, but it seems, fortunately, extreme, or even noticeable, foul ups are uncommon, that said, inversion agitation with some variation is prudent, and though I have never personally seen problems with bubbles, I avoid slamming the tank on to the counter as I have seen some do, any bubbles that tenacious can hang around. I have seen cracked tanks.
With shorter development times and larger tanks, I do try to make the changeover between solutions more efficient, better to gravitate perhaps to more reasonable times.
I like a hardener in my film fix as well, and it seems you may have to add one if you want it these days.
You acquire personal techniques as you go along, there are particular film clips I like, and others I do not care for, I keep extra reels handy, in case one is giving me a hard time on a particular day, I take another from the stack, I see no advantage in stop bath for film, as I do not use fix to saturation, and I have a way of using my small finger to keep the film away from the reel during loading to avoid scratches, I may mist some water on my floor and walls in dry weather to knock down dust before it finds a wet emulsion, and a final rinse is in distilled water with a wipe from some Swedish sponges I found and stocked up on years ago-- YMMV.
I know in theory the steel tanks are "better", but I have seen any number of lost exposures from folks' film sticking to the next row and keeping it from processing, I like the Paterson system of plastic tanks.
Find something in your comfort zone and use it.
I used a lot of D76, then Rodinal or R09 for MF and APX, just seemed a good tonality, but Xtol seems to do just about everything D76 did and better. I had been known to mix up D76 late at night from formula when I was out, and in the early days actually replenished my developers, but went to 1:1 and toss the used. Chemistry is cheap relative to results and effort.
I don't know whether all of this is technique, or tics I have come to use, and yes, I write long posts. ;-)
Regards, John
