Holy crap, 28% to dead that fast? That's insane. My iPhone did something similar last week but it was at 11% and I figured it was just the cold. Yours at nearly a third left is a whole different level of messed up.

My dad had a shower caddy from the 80s that outlived two house remodels and a divorce, and I swear the secret was he never cleaned it. That thing had a solid layer of soap scum so thick it basically became a protective shell. I finally scraped it off with a plastic putty knife and the metal underneath was perfect. But to your actual question, I drilled extra holes in mine and it just made the rust problem worse because water got trapped in the new spots. Maybe just accept the scum, or hit the seams with a toothbrush and some vinegar once a month. Honestly, the coating trick is the real win here, cheap ones are a scam.

Duct seal's great until you gotta pull it back out in July, that stuff gets like warm taffy and sticks to everything. Funny enough, I used a whole tub once to patch a leaky ice machine line at a diner, and the health inspector thought it was some kind of fancy gasket. Signal jump sounds better than my result, though, I just got a sticky mess and a customer who swore the soda tasted like rubber.