Okay, this is 1 of those things that just can't be proven. You can stick 50 growers in a room and you'll get a split room, same goes for flushing.
Really, I like to dry a plant whole and slow, so I water before harvest. but as for leaving the plant to dry in the soil, really, its down to your preference. I read some stuff about this before my 2nd round of harvesting and I bookmarked it as I thought I might try it on 1 plant. Hopefully this will help, its from a much more experienced grower that deals exactly with what you are talking about. He actually just uproots the plant from the soil, well DWC I think but he talks about many ways, I haven't read it fully as it's really long, but if you haven't been watering her for a few days, she's partly there, (dry wise) https://forum.grasscity.com/threads/bizies-best-way-to-harvest-dry-cannabis.1143213/
Before I would of said, always water before harvest to prolong the drying time but after looking up and researching I'm finding 90% of ppl are saying to let it dry out 1st and then harvest espically if you've flushed your plant. I'll try find a few extra links for u bro.
https://www.growchat.com/how-to-prepare-marijuana-plants-for-harvest/
I feel you'll find better advice by doing research on forums and so on, and normally you'll c 1 or 2 experienced growers that have many harvests with many different drying methods tried, as of now I don't have that, so hopefully you'll find something on here. I scanned through them quickly and they seem to have everything you'll need or you can take bits out that suit your environment and find your middle ground as these growers give advice from their environments.
Good luck pal.