I just need a small victory so I feel like I get this, in general.
Well, all things considered, you may consider yourself the winner ... for now

A side thought about mowing the lawn: if we replace "скосил" with "покосил" we'll get an absolutely identical situation as in "смотрел/посмотрел" (косил/покосил).

Скосил/Выкосил both have the result (no more grass on the lawn) hardwired into their meaning while покосил/косил don't.