Views will differ on that. Some would say that by sticking to one thing you get to know if that thing is being beneficial to you or not, whereas mixing things means that if you find benefit, you don't know what was causing it. However, some would say that if you find benefit in what you are doing, then why not just go ahead and do it.
I use lifeflow in my morning meditation and just meditate without for evening meditation, then sometimes listen to the optimal learning etc. additional tracks when I'm at work or reading as I feel like it. Works for me.
Hugs
Giles