fact is that each training will improve the players who played the position you where training. Even if you see no pops, the players still did improve.
By training more positions your players will get less training each time (logicall since otherwise everyone would train as many positions as possible each time), but it also makes more players improve.
Doing this you will see pops less often then training 1 or 2 positions. But to me, pops do not matter. the fact I know my players improve (even if not visible all the time), and the fact I upgrade my entire team in a balanced way with this system, is the most important for me.
So if you want to train a few players to make them pop as fast as possible, this system is not for you. If however you have a soldig base for a decent team, and are planning to try to shape that team, and are not training to try to sell for profit, then my system can be very rewarding.
First you need to identify where you need to focus training. Some pleyers will have need to other types of training more then others. Each player will have his preferred trainings to make him improve, and will have skills which not realy need improvement yet. Based on this, and on the minutes all players got that week, you can see which type of training wuold be most profitable for your team that week.
a small example with just 2 players: let's say A needs OD and driving, but doesn't realy need jumprange. Player B needs driving and jumpshot, but not OD.
Now if both players had full training, it seems best to train 1 on 1 since it trains driving, and both need it, and both have full training. If for some reason A has full minutes, but B doesn't, it might be better to train OD, since A needs it while B doesn't realy need it... Still B will improve, but not as much as A. Over time this will make both A and B more balanced.
this system can be used for any training, even if you train 1 position, and then it will be as easy as in this example.
I do this for my entire team however, and it's prety complex, but doable.
First I check which positions would get most profit from training, then I look at the available trainingtypes for those positions, then I look at what the players use most, and depending on their minutes decide which training is given that week.
This week for example I trained blocking, since I had 2 PF and 2 C with 48 plus minutes, while other positions where more divided (had a player play 3 positions and a few 2 positions... which happens often with players so balanced as mine)
It's a big task each week, but after a while you get used to it and see quicker what the preferable training is for that week. Also you need to manage minutes in the thursday's game as good as possible to direct training one way or the other, and it often happens when that fails that I decide to change my training after that game.
Again I must stress that this way of training does not pay off when you aim for selling players, but I honestly belief it is a great way to improve your team in it's totality. It's the minutes that other manager 'spill' by going for a training they decided a while ago that I pick up by making last call trainingtypes, which make it competable with the other system I guess.
They are not your friends; they dispise you. I am the only one you can count on. Trust me.