For the most part actual wall bouncing is a waste of time. We want to move in a straight line to the next opponent or kill it without approaching it. There aren't a lot of close cover areas that it would make sense to do so. There definitely some swifter movements that can be done sometimes, but in most cases we avoid it because either (a) Gears 1 is legit clunky af or (b) we're trying to stay safe on a decent pace. Also don't forget that just because one part can be faster doesn't mean we don't know. You can have a bad segment and still get a great run overall. That's why my SoB is like 5 minutes lower than my PB.
By all means prove me wrong though. Give us some timestamps and tell us what we can do better. Alternatively you could even get involved yourself! Join the Gears Speedrunner Discord channel and teach us a thing or two (or nothing and just do it better) by doing some runs. We haven't been super active on anything besides Gears 4 recently - or at least on the USA side. IDK what Live is doing in Australia lmao.

I've been known to float around on different games after several months of not playing it especially if I feel like I can have some good competition on something again. So if you've got some good stuff go ahead and show us.

I should check notifications more lmao. Slevanas answered the main reason that there are just extra chapters in the campaign.

Other differences that exist but don't affect the time that much:
Gears 1:
- More consistent Kim warp
- Seeder 2 skip
- Act 2 fight in the courtyard with a Boomer and some Snipers is often terrifying
- Slightly better Dom RNG in Act 2
- Before enemy troika you can run past an e-hole through a no-light zone to skip the fight
- You can run to the door behind the troika turret without shooting gas cans
- Act 3 Skip from start of underground to Corpser
- Able to take less damage before dying (hardest Gears game for not dying in any%)
- More RNG shotgun
- Clunkier movement and physics
- Double/Triple meleeing exists usually to a player disadvantage
- Flurby himself hasn't made guides for anything

Gears UE:
- Can't do Seeder 2 skip
- Act 2 fight in the first courtyard with a Boomer and some Snipers is wayyy easier
- Very risky to run to the door behind the troika without shooting gas can behind the dumpster
- No-light zone by the e-hole before the troika is blocked off. You have to go around and (probably) fight through it.
- Act 3 skip is only from after the Wretches to the Corpser (maybe 2 minutes slower)
- Act 5 introduces a bunch of previously PC-only chapters, but there are two decent skips in those parts
- Multiple sensitivities for look/aim/zoom makes shooting feel much better
- Movement is much nicer
- Grenades are less stupid and you're able to swag on RAAM much more easily
- Flurby himself has made guides for the skips

That's what I got off the top of my head 🙂