24 is just so long.
But also, my expectation is that a scammer is going to just automate the flow here anyways. Cool, you hit the "24 hour" wait period, I'll call you back tomorrow, the next day, or the next day and continue the scam process.
It might stop some less sophisticated spammers for a little bit, but I expect that it'll just be a few tweaks to make it work again.
There will be some proportion of people who mention to their spouse/child/friend about how Google called them to fix their phone, and are saved by that waiting period.
The question is, why exactly 24 hours? The argument is that the time limit is set to protect the users and sacrifice usability to do so. So it would be prudent to set the time limit to the shortest amount that will protect the user -> and that shortest amount is apparently 24 hours, which is rather.. suspiciously long and round :)
Unless you want to pick 1 week. But that's a lot more annoying.
Someone who lives in another timezone or works weird hours etc. Our routines generally repeat on 24hour schedules, so likely to be one point of overlap.