Empiricism: in 5 months of reserve on the 76T and 756 in EWR I have broken guarantee precisely once, after much effort, and by a whopping 2 hours.
You can pick up short call assignments for add pay up to a point (see contract) so if you are within ~2.5 hours of base that could be more lucrative than trying to fly your ass off to break guarantee. This technique is not fleet-specific.