The Geman & Geman result is a bound on the annealing schedule in order to guarantee an optimal solution. For some problems, we can do this with a faster annealing schedule, and in many cases when we don't need an optimal solution, a faster annealing may be more efficient.
A popular annealing schedule is one that is exponential rather than logarithmic:
This is sometimes known as simulated quenching. Usually, gives
quite good results as long as C and 
are chosen appropriately.