I loathe a metronome :lol:
Just seems totally soul-less and divorced from what happens when you play with other musical parts. If I have to use something to stay in time I use a drum machine.
But the main way I've avoided getting "stuck" is by writing songs - I've been doing it ever since I started playing nearly 40 years ago. I write stuff I can't play and then have to learn to perform it. Simple as that - to say, at least :lol: ... slightly harder in practice! (But I might be a bit different to many of you, though? - I picked up guitar to accompany my voice and to write songs, I didn't pick it up to be a guitarist... I AM a guitarist, but I rarely regard myself in that light when I'm using the guitar, I'm a songwriter/musician, whose main tool is a guitar)
But something else I've learnt over the years -
"what exactly is stuck?"
Most of it is in our heads. Try telling yourself you're not stuck, you just think you are (doesn't always work, though!). I've always tended to think "if I'm not enjoying it, do something else" - but that didn't stop me sitting there for hours doing the same stuff. In recent years, I can actually use this - I'm still driven to play the thing, but if what I do doesn't please me I'm capable of putting it down and not touching it for days or even weeks. Then when I pick it up again, it feels a little "alien" but it still comes back to me, in a "hey! this is good, why did I think I was stuck?" kind of way.