heat gun is the way to go for best results.
Also look for an adapter that goes on the gun, made specifically for shrink tube on connectors.
It's goes in front of the air flow - it's metal - and it curled like a C.
It forces the hot air all around the shrink tubing so you don't have to play contortionist to get all sides of the shrink tubing.
not a big deal for loose cables, but when in a tight spot - they're great to have.