I get bored buying the same thing the time. A while ago, though, I found a dishsoap I really liked and liked enough that I was ok only ever getting that one kind. (It's hard to find good lemon-scented dishsoap.)
But I'm almost out of it, and since I have to order it instead of buying it in a store, and I haven't gotten around to doing that, I've been supplementing by reverting to my old habit of buying something different each time.
Which is why I have three bottles of dishsoap started right now. Because I'm way too impatient to wait until one is finished before trying the new, different one.