I have 3 feeders & get lots of activity at all 3. they are constantly fighting & guarding what they consider "their" feeder. Now when the season is in full swing I won't get 2 weeks b/c they suck them dry (or very low) in 7 days or so. I watch for the cloudiness & change when I see it. No, they are not in a whole lot of shade but they get some shade during the day. The one out back gets the least shade & it goes bad fastest but it also gets sucked up the quickest even though I actually "see" the one out the kitchen window getting more use but I'm in the kitchen a LOT.
I have a friend near Montgomery, Al. who has those great big feeders & hers do get cloudy & believe me, she doesn't have any problems with them not using her feeders.
I do wonder if there is a big difference b/c we have so much less humidity here than anywhere else in Fl. that I personally know of. Maybe that makes a difference. I don't know. Okay, here's an example ---- I put my feeders out on the 3rd of this month & have been checking them every day. They are just today starting to get a bit of a haze so I will change them. So that's 18 days that they lasted. You have to remember too, that we have cool nights yet and our daytime highs haven't been all that bad yet -- well, it's been getting hot just the past few days but it doesn't *begin* the day hot like where you are Becky. We *get* hot for a few hours not the whole day.
