How to realistically assess personal effort?

quick question, when do you install a frost skirt please?
I dug a 50x60 trench, put in steel fiber concrete, done? Took 1 day for 2 people.
I only know this when people pour foundation and base slab at the same time.
Usually, a lot of sand crumbles back into the excavation then.

I'm not a professional myself, but that's what I was told.

1. When in addition to the frost skirts a soil replacement must take place.
2. When building on a gentle slope and several sides of the frost skirt remain partially visible.

Of course, this means you can't pour concrete against earth.

I only know this when people pour the foundation and the base slab at the same time. Usually, a lot of sand crumbles back into the excavation

As far as I know, every professional advises against pouring the skirts and the base slab simultaneously.

I'm not an expert myself, but that's what I was told. 1. If in addition to the frost skirts a soil replacement has to take place. 2. If you build on a slight slope and several sides of the frost skirt remain partially visible. That, of course, means you can't concrete against the earth.

Good, that's clear. In our area, we have sand/gravel, only topsoil is removed and refilled with fill sand and compacted.