While I do think foam rolling plays a part in every training session, do not get bogged down on spending too much time doing it. If you are tight for time out of all the components in what I prescribe, this would be first to go.
I do think it holds value for loosening out if you feel stiff or tight, and I am a big fan of foam rolling the thoracic spine as it generally provides some instant relief it someone is stiff there.
However, I put more value on a personalised dynamic stretching sequence that would help an individual target their problem areas. This should be first port of call before beginning your session.
A few key points on rolling – stay nice and relaxed while doing it, and move through it slowly in small areas. If you find a tight spot, work on it.
When the session finishes I would prefer the client to go through a decent post-workout static stretching routine, and if they’ve got time some foam rolling. The stretching takes priority though.
In summary, if you’ve got time to do it, good. If not, there are other things higher on the list of priorities to get done.