The one sentence paragraph, when overused, is a hallmark of bad writing.
They may be written all in italics.
They may just be short.
But, budding author, the one sentence paragraph does not add ironic poignancy to your writing when they're everywhere.
It makes you look like a student trying to cheat a page length minimum.
The one sentence paragraph does not make your plot race and crackle with tension.
It makes you sound like Christopher Walken.