it's true you can bring up the positives for the managers about doing what you ask them to. That is a thing that is never wrong.
on the other parts however, each person is different, and each person needs an other approach to reach your goal. The difficulty is that since this is the internet, and you don't know the other people well enough, it's a game of gamble.
So;e will continue if you persist, others will react the opposite way, even the slightest 'push' they feel will make them turn the other way.
In general, my personal feeling about this is, that when a manager is left open a wider range of options, they are more likely to follow your lead. tell him to do things on strickt terms, and he will turn away.
Managers like to follow all the terms the NT coaches give them in order to offer the best possible player. If you set a restriction that is too harsh, making the manager not comply to that 1 thing, he is likely not to care too much about breaking other wishes as well.
That's why my advise would be: ask what you like to have, but don't narrow his options when it has no use.
Narrowing his play-minutes to 60-75 to get an exelent GS is not needed when the GS would be equal if you'd ask him to keep the player between 48 and 77 minutes for example...
to end my discussion about this, a small example:
you ask that the NT player
1) gets full training each week
2) plays between 60 and 75 minutes
3) is trained with 1position training only
4) is trained in passing for the next 3 weeks
now, let's say the player is playing PG, and he has 43 minutes of play. The manager is still willing to put him up as back-up, not as starter anymore, but rather not play him in the next and last game of that week at all.
he sees he needs to get him 60 minutes, and knows he won't reach it with a back-up position, so to reach that criteria, he must put him as starter. But he realy doesn't want that at all, so he won't. Since he can't reach that, he might judge to just do what he likes best, not play him in the next game. It doesn't bother him that he doesn't get the 48 minutes for full training, as he didn't reach his limit for minutes anyway. s it turns out it might be even more interesting to traing JR this week, given the minutes of the players, and that means a 2 position training as well. Result: screwed up week NT-wise.
if criteria 2 would have been 48 - 75 minutes, he would likely have set him up as back-up, meeting ALL requested stuff and with no loss of GS at all...
I know this is a rather drastic and maybe exagerated example, but similar stuff might happen, and WILL happen if you set the limits to strickt. In the end the managers even will totally ignore your requests because it takes them too long to figure out how to comply, or it's not how they like to play, or any other reason.
Therefor, I like Revo's approach. If they say no, don't insist, unless their no means a total waste of the player. Because by pushing your luck, you might loose the player altogether, and will have to start over with an other one.
They are not your friends; they dispise you. I am the only one you can count on. Trust me.