Reply to Cut points when mixing live?

A Challenge I find in mixing is knowing the exact point to cut the live track and have the cued come in, and being able to do this bars and bar in advance. I usually try to start the next track 16 or 32 bars into the played one, and allow the structures to compliment one other. Otherwise, I'll just play whatever bar loop for the cued track, and drop the 1 of the cued onto the finale of a verse or build up of the track playing (hip hop type club - dancy mix context). But without the help of my software flag points, sometimes I miss the point where both should sync and everyone here knows what I'm talking about.

People always say "don't rely on the software, you should be able to do with by ear etc". Just wondering if there are some mixing techniques or helpers that I'm missing. Thanks!