It’s pretty straightforward for me to answer on your question. When you asked are freerolls good for training, the fact speaks for itself - yes, it is good for trainng as well as for the study, for bankroll foundation etc. But it is good for freeroll format touranments only. Of course, you can apply obtained learned behaviour and experience into real money tournaments but there are another reference coordinates and equations with n-unknowns, and you may not meet expected outcome based on your own improvement archieved in freeroll's games. Freeroll tourney is helpful for serviceability of your bankroll, as i said before for foundation, basement but not for development.
online poker is a business for its holders, and for us, clients, this is an entertainment. Therefore, as per related application mechanism, without investment will not be income. And when you decided to do poker=do money as one of the milistones of your budget, you have to play on real money and gain experience herein.
We can continue discussion in this subject matter following thread here:
https://www.cardschat.com/forum/tournament-poker-59/value-freerolls-tourneys-351131/