So ive been wanting to get into speedrunning and submitting runs for a while now, and ive read in a few places that if im recording a speedrun for leaderboards, im supposed to do the full speedrun at once, but im a teen and my parents dont allow long periods of gaming. can i pause the game at points where speedrun timers usually stop (for example, chapter ending art in celeste) and then edit together the recordings and submit them?

That would be a segmented run. Most games on the site don't have categories that allow segmented runs. Regardless, ask the game's moderators about this.

If you can't play full runs in one segment, due to how long they are; then two options:

• Speedrun shorter games. You can find many games where it takes between 1-30 minutes to finish them. You don't have to go for the 1+ hour games.
• Do speedruns of individual levels. For example in Celeste, you can submit a run of each level separately, and those of course will take much less time to run than the full game.

As Walgrey said, the majority of the games on the site require you to do a run in a single segment; so don't get your hopes up for it to ever be possible for you.

As Walgrey said, most games on this site don’t allow segmented runs. However, Celeste does track speedruns of individual levels. That seems like a great place to start for somebody with limited time.

Edit: Oreo beat me to it