Making this just as a quick resource for the 5 skips with all links available for them since some may seem a bit scattered.

There are 5 revisit skips/one cycles in crash 1 100%: Jungle Rollers skip, The Great Gate skip, Upstream skip, Rolling Stones skip, and Cortex Power skip. All runners should definitely learn Jungle Rollers skip and The Great Gate skip right away. They are very easy and at the start of the run (some runners struggle a bit getting some things in Jungle Rollers skip down at first but they always figure it out after like 15 mins at most). Cortex Power skip has undergone changes and discoveries that make it also reasonable for new runners to do, so that should be done right away too in my opinion. Upstream skip, in my opinion, should only be done at top-level for reasons I'll explain below. Rolling Stones skip was discovered by Lukademus in late 2022. It turned out to be even easier than Cortex Power and Upstream skip. A new section has been added to this guide at the bottom.

JUNGLE ROLLERS SKIP

This allows you to get the gem without having to revisit with the green gem from The Lost City (Hog Wild on NTSC-J). In my opinion this is the 2nd easiest to do of the 5 skips.

WHiP's tutorial:

Tutorial for my alternate method:

WhitePaaws' backup method:

THE GREAT GATE SKIP

This allows you to get the gem without having to revisit with the yellow gem from The Lab. In my opinion, this is the easiest of the 5 skips.

The tutorial linked below covers the current method for this skip. Before a user named SShotty found the current method back in 2015, the strat was to jump off the side(s) of the portal to get to the other side. This can still be used as a backup, however, if the turtle dies (which can happen if you get hit by the spikes since the i-frames will kill it) or you don't have a mask (or 1 mask if you're going for upstream skip). Methods to do this backup include zigzagging to the left side of the portal and jumping off, jumping on the right side then zigzagging to the other side, and jumping on the right side of the portal then the left side of the portal and then onto the other side.

WHiP's tutorial:

CORTEX POWER SKIP

This allows you to get the gem here without having to revisit with the blue gem from Toxic Waste. This is the 4th easiest of the 5 skips.

This skip has reached a point where any runner can learn it and go for it consistently. In the past this skip has either been impossible, TAS-only, not viable, or had some pseudorandom element we couldn't figure out (2016-fall 2018). But now, thanks to work of several runners (most notably The8BitBeast and Rex), we have a setup that makes the exit part of the skip 100% consistent with a perfect visual cue.

If you fail the skip you can go beat Toxic Waste and quickly go back to Cortex Power and do it normally. Though the skip is consistent enough where you should not be stuck in a loop of failing the exit, so you can also just re-enter and try it again reasonably.

The two parts to this skip are: The entrance to the blue gem path The exit from the blue gem path back into the main part of the level

My tutorial (covers both entrance and exit in detail):

WhitePaaws' alternate entrance method:

WhitePaaws' entrance with input display:

UPSTREAM SKIP

This allows you to get the gem here without having to revisit with the orange muffin from Generator Room. This is the hardest of the 5 skips by a long shot.

Note that this skip is a huge pain to learn and get good at. It's precise, annoying, you can get consistent with time but some days it'll still kick your ass. I'd only advise learning this after getting around a 1:05-1:06, or even more. Due to the amounts of resets this can add if you have poor consistency with the skip, you should be consistent at the rest of the game before implementing this. At the end of the day though it's your choice, just remember that understanding the diagonal theorem explained in the tutorial below is key to success with this.

This skip has 2 parts: Getting the box under the bridge with 3rd mask form The out-of-bounds trick to access the orange gem path (really hard to get consistent, not worth for non-top level runners to spend their time on).

WhitePaaws' tutorial:

ROLLING STONES SKIP

This skip allows you to get the gem in Rolling Stones without needing the blue gem from Toxic Waste. Also, by doing both this skip and Upstream skip, you can do Native Fortress 2 earlier and save a bit of time from that as well. This is the 3rd easiest skip in my opinion.

Check both tutorials and see which works better for you. You could divide this skip into four sections:

1. Getting into the pit (VERY easy - just hold forward off the middle without spinning or invincibility)
2. The turnaround fall into the lower section: The place with the boxes is on a lower plane than the one you initially drop onto. Note that you don't have to do a 180 for a quick turn when you fall off a ledge. A spin isn't required here either. Find your preference.
3. Getting the crates
4. Getting out of the pit without dying. This is the most complicated part but can be made super consistent.

Lukademus tutorial:

Klaxxy73's tutorial: