I think there was some talk regarding that back when people were running palace all day, back before SE tweeked the chest. Something of the sort that the higher your level is, the better chance the silver chest wont explode/ will give you a better chance at +1.
People have come up with all sorts of mad theories about this event because it's absolutely crammed with RNG.

One of the worst I've seen was someone attempting to rush through the floors because supposedly it made it more likely to get better random floor effects, whereas taking too long would cause you to be more likely to get penalizing effects.

You just know that some of these people are the type that hold Up and B while doing a handstand every time they throw a Poke Ball.