It varies based on everything. One position training or two? What type of player? How tall? how old? Is their skills high or lower for what you are training? Elastic effect in place? what level trainer? Is he close to capping?
I personally expect a pop or two every single week between my top 3 trainees, but that is also because I am doing a lot of 1v1 training so more pops generally occur. There is no such thing as a weekly average for pops though as there are too many other factors involved.
Murray/Harris/MPJ/Grant/Jokic - 2020 NBA Champs