Electric guitar: How many speakers?

Here is a question about electric guitar that I’m finding it very hard to find a credible answer to. Say I have a single amp-head and I’m not doing anything stereo. In what situations should I choose a single speaker cabinet? When should I choose a cabinet with two speakers? When should I choose a cabinet with four speakers?

I understand the trade-offs between the different sizes of speakers but not the different numbers. Indeed, the only thing that seems clear is that multiple speakers cause problems with phase cancellations.