Do tight beads actually tell you anything, or is it just looks?

I'm firmly in the calendar camp after getting burned by trusting my eyes. Last year I had a sealant on my daily driver that was still throwing nice beads at the four month mark, so I figured the protection was fine. Then I clayed a small section of the hood, and the difference in smoothness and the way the water sat on that test patch told me the actual layer was way thinner than the beads suggested. Beads lie because they can hang on to residue from the last spray wax even when the real barrier underneath is done. What I do now is simple: I log the date I apply anything in the notes app on my phone, and I plan reapplication based on that, not on what the rain shows me. If I get four months out of something in summer and two in winter, that's my baseline. That said, I do peek at how the water behaves, just not as proof of anything. Sheeting off clean is a nice bonus signal, and tight beads that slowly go lazy and patchy over a few washes is my cue that the countdown is nearly up. It's a weather vane, not a gauge. For your situation, if the coating is a few months old and you're feeding it with a spray product regularly, you're probaly fine either way. The beads looking good plus a fresh-ish coating date means you can relax until the calendar says otherwise.

I'm with the sheeting folks, but for a slightly diferent reason than what gets repeated. When I had a coating on my daily, the beads stayed tight for ages even after the coating had worn thin in spots, because I was topping with a spray sealant every few washes. The topper was doing all the beading work while the base layer underneath was basicly done. So on my car, tight beads told me my spray wax was alive, not the coating. The test I trust is the bucket-and-hose check on a cool panel. Flood the hood with a slow trickle of water and watch what happens over the next minute or two. If it gathers into heavy rivulets and rolls toward the edges, leaving the panel mostly dry, you've still got real protection. If it splits into dozens of scattered beads that sit there and cling, the surface is aging out even if those beads look pretty. Glass is my other tell. The windshield gets the most abuse from wipers and it never lies. When the coating on mine was healthy, rain at highway speed blew straight off. Once I was getting streaks and the wipers started chattering, I knew it was time to reapply regardless of how the paint was beading. Honestly the spray wax habit is a nice safety net either way. Even if the coating is cooked, a fresh layer of topper buys you the water behavior and some sacrificial protection til you strip and redo it properly.

The thing that settled it for me was doing a strip wash with a dedicated degreasing soap instead of my usual maintanence shampoo. Before that my car beaded like crazy and I assumed the coating was thriving. One stripped panel later and the truth showed up fast, water was flatting out on the hood where the topper had been carrying everything. Now I only trust what the paint does right after a strip wash, becasue toppers and rinseless products both leave film that fakes the look. If yours still beads or sheets clean after that kind of wash, the base is doing real work.

I go by how the car dries, honestly. When the protection's alive, water mostly runs off while I'm driving or I barely need the blower. When it's dying, the whole car's covered in droplets that just sit there waiting for a towel. My wife's car has the same spray stuff on it as mine and hers gives up way faster because it lives outside, so I stopped comparing panels and just watch how each car sheds water on its own.

The detail that stands out to me in your post is the glass. On my own car the paint will fake it for months because of topper residue, but the windscreen never lies. Anything I spray on the glass gets wiped off by the wipers within a couple of weeks, so whatever beading is left up there is coming from the base layer. Mine lasted about nine months before the windscreen went flat while the doors still looked great. Check how the rain behaves on the windshield at highway speed. If it's still rolling off there, your coating is genuinely alive and the roof beads are just confirmation.

Update: tried the strip wash test on one panel with a stronger soap like the third poster suggested, and it told the truth. The hood flattened out but the roof still beaded after, so my coating is actually fine there and the spray wax was doing less than I thought. Also started watching how the car dries after a drive now, which is way easier than guessing from looks alone.