Everyone is going to have different needs and tolerences. i don't know how heavy my pack is now, but here's what i do:

whenever i add or change gear, or have to deal with an injury like i have for the last six months, i test it with a hike, see how it feels, readjust, and then take another test hike. the time to be sure isn't during an emergency.

i also build in options, like a lightweight, bag stuffed in that can hold non-essential redundancies, should something like an injury happen along the way. that way, i can easily shed gear and cache pass it off on someone else if i need too.