for me there is no One Perfect TSS / CTL that i find is tolerable. It all depends on the makeup of the TSS. E.g., TSS that consists of only aerobic hours, could be 6, 7, 800. However much time i have available, i can use it, and it’s NBD. I might not be fresh; i might not put out good power or win any races. But nothing bad is gonna happen.
Conversely, if the TSS is made up of hard intervals, it could be 400 or 500 that becomes too much, if i don’t leave enough recovery in between sessions.