That's a great point, and as someone who is a happy Fluticasone user I know exactly what you mean. It took me about a week or so to become fully used to fluticasone, and ever since then my allergies have been mostly non-existent. I can breathe normally practically all the time, something I didn't realize was normal!
But yeah, my doctor didn't say much about it other than "you need to have a checkup every year so we can review your nasal passages and mucus membranes." She said "Two sprays every day" and when i said, after a 3-month checkup, that it didn't seem to be doing much, she asked if I was doing it every day. I said "no, I forget some days, it's been more like every other day when I feel a little allergic." She just reiterated "Do it every day."
It would have been nothing special for her to spend 10 seconds saying "This drug requires a build-up in your body for it to function, so if you skip days, it reduces its effectiveness." Instead, I just got a rule that I was told to follow with no real explanation.
I've had one doctor who was really, really good, and sadly I only saw him twice. I went for a checkup, and when he asked about my exercise level I told him I had just run a marathon a month ago. He said "Why didn't you tell me that at the beginning and we could've skipped all of this! Why are you even here? You don't need a physical!" That's when I told him I needed to have a physical just for the fluticasone... I did see him again to get a prescription for anti-malaria medicine, and he told me about the 3 current ones, the side effects, when to start taking them, and after selecting one he said "this will make you feel a little crappy. You should take it for 3 weeks after you get home, but if you don't go out in the countryside and you're feeling crappy, just take it for a week after you get home."