Whoever came up with the drill and fill method should be shot on sight. Or even better, drilled with holes and filled with something painfull, and then shot. Yes I'm bitter.
All the deck area on my boat was drilled with holes in a 2x2in grid pattern and filled with epoxy. The decks were not soft, so maybe this method does "work". However, there were large areas of rotten core, and soaking wet core. I probably pulled gallons of water out of my decks. The boat had always been stored inside heated so this wasn't an issue. I have no doubt that one winter in freezing conditions and the boat would've been FUBAR.
So I'm doing the proper core repair, cutting the top skin off, pulling out the balsa core and replacing. Not a bad job really, but made so so soooo much worse by the idiots doing the drill and fill bs. Really fun to pull the top skin and the core out when you have an epoxy column to cut through every two inches, and a pile of nasty half rotten wood half epoxy layer on the bottom skin to grind off. Someone's previous "repair" has increased the time on my end 10x easy.
Drill and fill should only be used in delaminated areas that have a completely dry and sound core. Otherwise you're just giving the finger to whatever poor sob comes next.
1978 Ranger 28 and a fleet of Mini 12's.
Ropes and rigging and splicing, oh my!