the only reason i can think of them putting in smaller pl's is when they finaly put in the other transformations
think about it if u go ssj3 as goku ur pl will most likely kill all those around u just from putting turbo on, lol
also depends if they use the base ki to make u transform to a higher level or the previous level as the base.
ex:
norm - ssj, norm is the base, ssj is the multiplied thing of that
ssj - ssj2, ssj is the base, which would make ur pl jump a lot
ssj2-ssj3, forget about fighting a ssj3 he will kill u with a ki blast
another thing could be ssj is a x2
so they could make ssj2 a x2.5 or x3
and a ssj3 a x3.5 - 5
makes sence dont it, but with a high starting pl ull be maxed out once u hit ssj3