Disclaimer: I may be misunderstanding the current semantics but I
1) did read the manual and 2) do use Automate and it mostly does what I
want (so I do at least hope that I "get it right")
As it stands now there is an option to run one's flows at startup but there is no way to explicitly exclude some flows from doing so, it is done implicitly as far as I understand (flows that have been successfully started and are running are resumed on next boot, flows that have been, at the moment of reboot, not running are not)
I think it would be nice to have a checkbox, in the entry point configuration options near the "allow parallel launches" and "don't show in list of starting points", that would explicitly exclude a starting point from automatic launch ("ONLY allow manual launch from this block")