When the woofer and tweeter are mounted on the same baffle, the acoustic distance is the same when you listen directly on-axis with the midwoofer. On-axis with the tweeter, the tweeter is closer than the woofer. In between the woofer and tweeter, you're still slightly closer to the tweeter. But when you're on axis with the midwoofer, the acosutic sources are both exactly the same distance.

The midwoofer of a two π tower is just about perfect ear-level when seated. That's where you want a one π or two π speaker to be.

Naturally, if you angle the speaker back or mount on two different baffles, these relationships change. You should set them where the path lengths are equal at the desired listening position. You can angle up or down the line of path length equality by moving the tweeter forward or back.