If I'm there to bring in wood it's generally a two person job, one to cut another to position and stack and once the chainsaw starts it's on and cutting until the tank runs dry with fairly minimal idling time.
There's a lot more idle time when cleaning up firebreaks, it's moving from tree to tree and often the branches that need clearing require a ladder or standing on a cab roof or in a hiab bucket to reach.
Also, with due respect, you've never been present when I or my father have cut wood, shorn sheep, loaded hay, or otherwise worked in the field. These activities get optimised via repetition to have minimal slack time and maximal throughput.
With an assistant the chain rarely stops, as one cut is completed wood has been positioned already for the next cut .. perhaps you've never been that efficient.
It's not possible to clear five tonne of cutting and splitting rounds in a day without minimising dead time.
Perhaps because when you're using a chainsaw you're rarely actually cutting all the time? Most of the time is spent setting up and moving things around.