*slams back a coffee*
Ok you know what? Random headcanon time to get shit moving again on this account. Again, these are personal headcanons and not something that appears in canon.
The amount of bloodbeads a revenant needs varies depending on their health and how active they are. If they're particularly active (such as fighting and so on) they'll need to feed sooner than someone who spends most of their time being idle. Also reviving and healing from injuries also increases thirst.
Protag needs a lot of upkeep in comparison to a regular revenant. For all the benefits they have, they also have to deal with an increased thirst that keeps them on the lookout for more beads. They may or may not find themselves constantly snoozing to offset the effects in their downtime.
There are areas that we don't see that are for the most part settled. Communities that have setup around bloodsprings that haven't withered that act like guarddogs for human shelters. Heavily regulated and a lot of the revs that we see struggling on their own are either outcasts or have their own reasons for operating independently.
Revs can eat food and actually get some benefit from it (Yes I know canon says otherwise but bite me). Eating food won't stave off the thirst or frenzy, but it gives the parasite something to work with when it comes to tending to the body passively. Well fed revs will see an uptick in their energy and healing from wounds is far less dire to their thirst.
Revs can actually safely drink very small amounts of another revenants blood but its like drinking saltwater. It can make your thirst even worse and overconsumption not only has the risk of frenzy due to thirst but drinking too much from another rev can lead to accidentally taking in their code and for most the incompatibly is incredibly dangerous.