I've been using this ai https://www.opus.pro/ to automatically cut up my longer Youtube vids into clips. Sometimes the results are great, sometimes not so much. I've seen really tremendous results using shorts on Youtube in the last few weeks. It's the lazy way, and I'm sure it's better to edit it yourself. But if you're curious about shorts, I highly recommend trying it and posting 1-3 shorts a day, cut from your longer content. It only takes about 2 minutes a day.
In the last week I've gained around thirty new subs, and close to ten 5k YT views from shorts alone by repurposing with this ai.