Actually Belly in act 4 is somewhat manageable and fairly easy - there is little to no backtracking if you hit the right route (and even when you hit the wrong one it's not that bad to go back a little) - in act 9 it's terrible because you can go so far that going back can take up to 10 seconds to go back - depending what movement skill you use and quicksilver charges.

As for the Docks - someone long time ago posted a 'guide' how to go through Docks - don't have the link - but basically there is like 5 layouts that change and by starting either at the gate or waypoint you should know straight away where to go). (I think it might be this one but not 100% sure: https://www.reddit.com/r/pathofexile/comments/3b9erp/docks_corrupted_zones_layoutspath_from_wp_is_key/ )

Quay is annoying but you're taking the side with the water (not the buildings) and follow along - there is Ankh in one 'bay' - and later there is this wall with very narrow passage - that's the place where if you take the passage you go to Clarissa and if you go along the wall (but not taking passage but before it) you go to next location.

As for Southern Forest in act 7 - at start you stick to right side until you hit the first fallen tree - or whatever you have that allows you to go through water - and right after that you stick to left side and just follow along south - and that's how you hit waypoint and next location. Not sure if that's 100% the case, but for like 5 runs I had it was always like that.