as Prostar pointed out, depends which algs you use, but
my understanding is that the 4 G-perms comprise 2 pairs of algs which are sort of mirrors to each other
so if you start with a solved cube
and do one of a pair of the algs, the other alg in the pair will solve the cube back again, and vice versa
so you can actually practice both algs in a pair, over and over, and then reverse which alg goes first...
this will also help you to focus and gain better understanding for recognition
once you get comfortable with your memorization and performance with the first pair of G-perm algs, you can switch to the other pair
you'll have them down sooner than you might think