These were a recent set of videos I had seen, saw the OPs post, and passed on the links. I don't think the original youtuber is on phototrio. I am finishing a 2.5L C41 Tetanal kit and deciding between Fuji Hunt vs Flexicolor.
Just from doing a little more research today, the videos are recent, Jan and May of 2020. The chemicals he is using are the currently available chemicals that may or may not be in stock at Unique Photo in NJ, and were originally meant for high volume with replenishing. There is a set of SM tank Flexicolor chemistry, meant for small tank processing, but these seem harder to find. He and others are simply using the high volume chemistry in small volume tanks.
pentaxuser, Looks like he makes 1L of working solution developer and uses it like he would a press kit, i.e. use and then put back into his pink bottle, no replenishing, and he gets 20+ rolls from that. When he is talking about storing for over a year, he is talking about the concentrates. My understanding is that LORR C is the one that is susceptible to oxidation, easily displaced.
jarrett: The starters, developer and bleach, were intended for freshly mixed chemicals, to bring them closer to their equilibrium state in a high volume, regularly tested system. Developer starter contains a restrainer, bromine, which is not present in a freshly mixed batch of replenisher/developer, but accumulates as you develop film. I think of it as the 3:15 developing time is the equilibrium of a replenished system, i.e. you replace the amount of developer so you can always just use 3:15. Fresh replenisher/developer WITH starter will give you the 3:15 for your FIRST roll, but WITHOUT starter, it might only be 2:30. Someone may have figured out times for developer without starter, I just did not find in my short look.
Bleach starter is a pH buffer. Short answer, PE and other phototrio users says it is not necessary. I'm good with that.
In regards to number of rolls. As both Mr Bill and Donald Qualls have mentioned, if you need the highest quality, that can be reproducible, stick with the original guidelines. I split my 2.5L into 3 x 800cc aliquots. I did 16 rolls with the first and 14 rolls with the second one, both more than the suggested number. Like Donald, I don't have those special eyes that see subtle variations in color and I use digital post processing, so I don't mind pushing the number. I ended up freezing those chemicals, in case I want to test them down the line. I remember watching a video of someone who pushed it well past 30 rolls for a 1L kit, basically until he lost a roll. So depends on your priorities.