To give a hard and fast rule for this and such types of questions strikes me as not a good idea. If one wants to implement some automatic check or the community is very large, then one has to decide such things, but as long as we are small enough as community to discuss things on a case by case basis I think this is the better approach.
Still the decisions made by others can serve as a guideline: 50 questions in total per month (technically over the last 30 days) is what a user gets on SO as absolute maximum, and this is considered as rather more than enough by those that set it. So, let us take that for the sake of argument, and since 50/30 a day is the absolute max, maybe a question a day is still quite a lot.
If we in addition agree that type 2 questions should rather be the exception relative to type 1 questions -- and I think we agree on this, I mean we created a site for mathematics education for a reason, we also could have joined or created a general education site -- well then we see that such question should be asked (per user) significantly less frequently than at a rate of one a day.
Now, during private beta, right after joining, and a like, things can be a bit different. Or, I would find it a bit silly to artificially delay somebody asking a general follow up question to a general question just to not exceed some self-imposed quota. But as a rough rule of thumb I would say significantly less than once a day.
That being said let me add that I consider the splitting of questions in type 1 and type 2 questions not as clear cut as suggested and there are other considerations too.
Namely, a question can be not only not very specific to mathematics teaching but it can be even not really a question on teaching, but a question on academic life that somehow involves the fact one is teaching.
Now, I do not even mean to say we should never admit such a question. But then, it feels less on-topic than a question that is at least directly concerned with teaching (even if general).
Further, considerations of quality could also play a role; the tolerance towards questions that are general but otherwise great will/should be greater than the tolerance towards not so good general questions.
Long story short: I think to attach a hard number to this is not the way to go. Once an activity of some user is perceived as disruptive or a distraction, users will and should speak up (in a tactful way), and then let us collectively take it from there. Conversely, users should pay attention to critique voiced by others, for example expressed via downvotes (yet should also speak up if they feel targeted unfairly or also just do not understand the situation).