My idea is: His ability is that, he has to clear certain conditions and then, he can get the easiest/best conditions for any ability he wants. That way he is basically making Nen itself offer the most efficient condition for any ability. For example, someone like Kurapika regrets some of his conditions for his ability. some of his conditions might be pointless or inefficient, that's because even the creator of qn ability doesn't fully understand how it works. But Ging could find the easiest way for every nen ability by making nen itseld give him the easiest solution.

So he could do unlimited nen techniques but has to clear 2 sets of conditions each time. 1 for his ability to give him the conditions of the technique he wants to use. And second the conditions required for that technique itself. That makes him extremely versatile but also makes his plans extremely compilated to pull off.