I got a few requests over time for 2 nights a week, which may shift around every week. People get such work shedules and it is much nicer if you have familiar places to stay. They ask, that's normal. Most hosts won't commit to block 5 week nights for 2 booked, but it may happen, that they find a host , who does it for a bit of company, not aiming to be fully booked.
I react like you do. I have a few regulars, coming now and then, guesting with other hosts in between, when my room is booked. I believe none of those started with such a request. I had one, who asked like that, came the first time and tried to haggle over the price, as he will become regular. Not so, thumbs down for other reasons and don't come back. ( I give thumbs down only in exceptional situations)