I didn't know S3 vs S0 but this may be the reason why I never keep my laptop in sleep mode and I prefer to put it in hibernate. What about hibernate? Couldn't it be an alternative to the "legacy sleep"?
Hibernate mode takes a long time to enter and exit, as it involves writing a lot of data to disk and then reading it back upon resuming. The whole point of Sleep mode is that it's fast: you just close the lid and you're in sleep mode, saving power. Then if you want to check something quickly, or resume your work, you just open the lid and in a few seconds or less, your computer is fully operational again.
Well, you're right but of Sleep is impractical with S0 mode as explained, hibernate with slightly longer transition time may be acceptable. Hibernate has really became fast on modern computers.
You're in luck, Windows shutdown is now actually hibernate (and has been for a few years). So if you just shutdown your laptop, you've been using this hibernate for a while. Turns out all those people saying "shut down your laptop before you close the lid!" were actually right.