Show new cards after review vs Mix new cards and review

Just a question for experimented anki users: I assume that there is no “best” option, but, which is in your experience the effect of both options in long-time memory terms? Which option do you personally use when you’re working with LOTS of cards, and why?

I mix them, because if I do new cards at the end of my session, there are no cards to fill the time while the learning steps pass which means Anki will show them again immediately.