That's why "staying on message" doesn't work any more
The electorate is too fragmented. Whether it was shrewd reading of the landscape, or he just got lucky and had the right style to take advantage, Trump's throw-everything-against-the-wall style works for this environment.
If you could interview 100 of his followers and figure out what really mattered to them when they decided to drink the kool-aid, you'd probably get at least 50 different answers. He throws so much shit at the wall that people can pick and choose their reasons, and there's something there for everyone.
For Biden, there's not going to be one message that resonates with "the undecided" because they've all got different reasons, too. (Though Trump is so polarizing I don't see how anyone can still be undecided about him, but that's a whole different psychology dissertation.) They need to hit on everything: the taxes, the campaign violations, the money to his family, the money to his businesses, the cozying up to dictators, the constant lying, etc. etc. etc.
Suppose each Lincoln Project commercial makes 1% of viewers say, "OK, I've had enough," I'm sure they've got more than 100 spots by now. The challenge is getting undecideds to view them.