Today will be the first day I've messed around with refreshing on
MDE in 6 months, but if I recall, it actually won't make a difference if you hit the same time or a different one. Say it's 11am when I do it, and I click on 3:00pm to search. I could be wrong, but if memory serves,
it'll look for anything available that day. If it spots anything between 11am (current time) and 4:00pm (one hour after my desired time) it'll just show me those times right away with no wording. However, if the only things it finds are times more than one hour after my desired time, it'll still show those, but above those times it'll say something like "We couldn't find the times you wanted, but here are other times available", and there's a little yellow triangle (or something like that) right next to it. It'll do the same thing over and over and over if you keep hitting 3pm. It'll show you everything available, the only difference is in how it displays it.
That's how I've learned to be able to really do it without having to completely stare at my screen endlessly. If I'm looking for a 4th, 5th, 9th FP+ it's usually for something I want to get on
right now or within a few minutes. When I refresh, if I see that little yellow triangle, I already know it didn't find anything within the next hour, so I just refresh again.
Hope that makes sense.