Replying to Question About Photo Sets/Series

So I have a series of photos from a hike I took last week and I've been going through them and I like some of them more in B&W, whereas others are better in color. Is there an unwritten rule that an entire series should be B&W or color? It's really a hobby of mine so I'm not too worried about selling them or anything, but, to me, it looks kinda weird flipping through a bunch of B&W photos and there are a few color ones in there randomly.

I kinda just convinced myself that they should all be similar, but I'd like to hear some input if someone has some wisdom to add.