Google says it couldn't verify the account is mine, every single time

Is there an Android phone or tablet anywhere in the house still signed into that account? Even an old one in a drawer. Keep pressing Try another way and one of the options is often a prompt sent to that device, which gets through way more often than the questions. If it's a school or work account, skip all this and ask the admin, they can reset it.

Waiting does help, mostly because lots of attempts close together make the account look like it's being attacked and the system gets stricter. A few days apart, from the same laptop and wifi each time, is the right idea. The other thing is whether you're getting offered a different route each time. If it's always the same dead end, it usually means it wants something you can't give (an old phone, a recovery email you no longer have). In that case keep trying periodically, but start thinking about a new account and moving your stuff over, because there's no one at Google to plead with.