The thing is, each case is unique and there are many variables...
For example, my AOS was relatively fast, around 8.5 months. I was lucky, somebody who filed few weeks after me, probably was affected due to COVID. I got appoved few days before the lockdown started.
With I-751, the processing time was 7 months when I filed, but I ended up waiting 20.5 months. All cases in my batch were delayed by 4-5 months. Somebody I know filed case 2 weeks after me and got approved 5 months before me.