You still have to expect variations in flight paths though.
Sort of a stale thread, but I thought I'd add my two cents in case it was of interest to anyone.
I've used all the apps (Go, Litchi, Autopilot, on and on). I keep coming back to Litchi because of it's browser-based Mission Hub. It can't be beat. I'd probably switch to Autopilot if they offered something similar. Anyway...
I've been very nervous about waypoint accuracy during missions. I don't fly too close to obstacles but, to me, 50 feet is awfully close when I'm a 1000' feet away and have no visual perspective. So I've been doing a bunch of test missions flying to various fixed points and comparing how close the drone is to them as opposed to where the waypoint was placed via the map on Mission Hub. I've done 30 flights over 6 different missions. The missions range from just 2-3 waypoints over a few hundred feet, to 25 over 2+ miles. The waypoints are all small fixed objects that appear clearly on Google Maps so that I can accurately place it in Mission Hub. All flights were done with 13-17 satellites and nearly calm wind. Altitude varies 50-125'. Camera recording and pointing straight down so I can review where it hovers.
The results?
**** impressive. Out of the 30 flights and ~350 waypoints logged, I would say that the drone hits each waypoint within 2-3' at most. The waypoint placement accuracy is dead nuts on in Mission Hub (the waypoint position appears to be recorded at the bottom pointy end of the purple tear drop). I would say after all that flying, not a single waypoint was missed by more than the 2-3' figure.
So, I certainly trust Litchi a fair bit more than I did before. And, the RTH worked twice to perfection. Both times when I lost signal ~1 mile out (100% stock RC & AC). After cleaning my shorts I decided to let the RTH play out. Both times the drone landed within 5' of the home point.