quiet enjoyment, so tell them no! Having constant viewings is so disruptive and you're not being selfish at all.
We rented a 2 bed house out, and a month after we moved in the landlords told us they had moved in with family, with their 2 children to make money out of us to get a deposit for a bigger house as it was completely unreasonable to expect 2 boys with a 2 year age gap to share a bedroom and was like living in poverty, telling us with our boy and girl in that same room. We had 18 months of viewings, it was awful.
Rented somewhere else, 6 month tenancy, we made it very clear we would be moving out after 5 months and our security deposit could be used for final months rent, the house was an absolute hole! when we moved in, and the landlord told us it was the benefit to be the first to rent it since he bought it! From the time we moved in we were beyond certain we would have to fix and clean it to such an extent there was no way our security deposit would be needed. Despite the landlord having a month's rent for an empty property, they wanted to do 18 viewings in one day! before we moved out, this was the 5th house we rented and we just took the hard line of no, no viewings, nothing.
For what its worth, over the course of renting 5 houses, we tried to accommodate requests, and for our troubles we had our childen's toys stolen, visibly dirty children going through our underwear drawers, kids bouncing on my children's beds with their shoes on, grown adults doing a no.2 and not flushing, viewers asking us for snacks for their children, adults accidentally breaking things, we even had viewers come back to different times in the day unannounced for another look. Hence just no.