TL;DR
One should be able to upgrade or reverse the direction of a segment of belts other than replacing them one by one.What ?
I suggest that double clicking a belt on top of an existing belt does not only replace the belt piece but replace all the belt pieces in that segment of belt.When replacing a yellow belt by a red belt all the yellow belts in the segment would become red. When replacing a belt with one going the other way all the belts in the segment would reverse direction.
In the case of an upgrade a segment could be all the belts where an item can be placed to reach the belt that was clicked and all the belts that an item can reach from there if not picked up by an inserter or blocked by some circuit logic without changing belt colors. Splitters and underground belts are included in this. So if you have 2 yellow belts, a red belt, 5 yellow belts in a line and you click on the first yellow belt then only the 2 yellow belts get changed. That way it would be easy to only upgrade parts of a larger segment by upgrading the ends first and then double clicking the part that should be upgraded.
When changing direction a segment is both more and less limited. For the direction the belt color does not matter. But a splitter can't simply be reversed. So a segment stops at a splitter. Side loading a belt can't be reversed as well. But the reversal operation could continue on the main path and leave the side loading path as is. This might be more practical than stopping at a side loaded segment. So for changing direction a segment is everything drawn as a continious belt excluding splitters.
A segment could be limited by the players reach and not work on the map view. In that case though I would like if the change could also be blueprinted and done by bots.
Why ?
A single belt tile can be upgraded or reversed simply by placing a new belt over it. A straight belt can be changed by pressing the mouse button and running along the belt simply enough. But when the belt has underground belts or twists and turns then one has to constantly stop, switch to undergound belt, replace that, switch back to belt, rotate belt to the new direction after a turn and continue till the next interruption.This quickly becomes tiresome and error prone. I often reverse belts after placing a blueprint as a way to mirror/flip the blueprint in which case they can be long, have many twists and turns and lots of underground belts.
