I was a bit undecided, but went with "3-5" and "a few sentences".
For this purpose, I am considering "house rules" being actual rules changes. There was a time when "house rules" was mainly used as a term for stuff related to the game but outside the actual rules of how the game action itself is played (and typically not mandated by the books), such as what happens to an absent player's PC, how to distribute treasure, or what level do you create a new PC after you died. I am not going to consider this kind of house rules against the number here, because these are things that every group eventually has to decide one way or another.
Then, I also need to make a distinction between changes and additions. The latter rarely bother me... for instance, if you want to add more detailed rules on how different weapons & armors interact with each other, or rules for lingering wounds, or crafting rules and so on, usually I am OK with those "modular" additions. Whether they work well or not, we shall see, but in general I am not against using those as a way to characterize a campaign differently.
However, rules changes can be either done to give your campaign a twist (as in "let's try to see what happens if we change this", which is fine by me), or because of a perceived necessity to "fix" the game. If I get the feeling that the DM thinks they are better, and they are "fixing" the game, I would rather not play with them. And it is usually very easy to see when that's the case, because they are always very keen on explaining why they are changing those rules, typically because they say something is either "underpowered" or "overpowered". I'll still play if it's only a very small bunch of changes, but if it looks like I need a written list to remember them all, forget it.