How much warm up do you need?

Hello guitarplayers i would like to ask a simple question (okay maybe it aint, maybe it is, i don't know)

How much warm up should i do before i play all the stuff i use to play. I play alot in legato which is my prefered speed method.

It just seems to variate alot from time to time how fast i am on that particular day, and some days i feel somewhat uncomfortable with my playing and speed. Can the warm ups have something to do with this? and how should i warm up the best possible way?
And how should i speed up my legato? :)

It always varies. Sometimes you'll pick up the guitar and get warmed up within 5 minutes. Other times you could sit there warming up for an hour and only then start feeling comfortable.

I just do different finger exercises to warm up with. Or go through different scales. I'll focus once on my fretting fingers, then another time specifically on my picking hand.

As far as speeding up legatos. Just practice like everything else. Spend a lot of time just doing legato exercises up and down the neck to a metronome, then increase the tempo slightly each time. Same exact formula as any "How do I get better at ___" question. Practice, practice and practice some more.

edit: and then practice even more

It depends on the weather too. Summer time can be only 5 mins while winter time it can be up to 10 - 20 mins.

About speed, start from the speed that you feel comfortable to play and then gradually add up to your maximum speed where some mistakes occur, and from that speed, slow down and notice as well as correct those mistakes.