Your lilies are just being lazy. They found the vase wall and decided to take a load off.

Yeah, that's a solid point about the wall prep. When you checked the backs, was there any adhesive stuck to them at all, or did they come off totally clean? If there's nothing on the tile, it means the bond failed right at the wall surface, which points to dust or maybe some kind of sealer that wasn't scraped off. A little leftover glue dust can ruin the whole grip.

I always figured napkins were good enough for quick math notes. That changed when I spilled coffee on a napkin full of equations and lost everything. Now I get that proper paper keeps your work safe and makes it easier to read later. It also feels more serious, like you're really treating the math with care. Plus, with good paper, you can go back and fix mistakes without the whole thing falling apart.