see the meiri.
Also if someone has a set time to learn that is included in this din of harei zeh mischayiv benafsho. That is why it applies more so to yungeleit. Kach kebalti merabosai. If I have the time I will look for more mareh mkomos on the subject.
as far as seminaries are concerned we are discussing 2 different things macro and micro. macro of course they have a say in its the implementation where things go awry. A lot of mechanchos are overzealous in their charge shelo kadas ukedin.
In response to all the posters who assume that a person who batels part(s) of the day should still be in kollel ask your rav/rosh yeshiva you maybe very surprised with the answers you receive.