Improving the system: Store more than 10 Upgrades
General ideas described in https://community.wayfarer.nianticlabs.com/discussion/15568/improving-the-system
There are people that might review a lot but at that moment they are not sending any nomination, so when they reach 10 stored upgrades they lack that incentive to keep on reviewing. An upgrade is something hard to reach and by itself it's not useful, you still need a nomination slot, so increasing the number of stored upgrades would be beneficial. At the very least I think that people should be able to store 20 upgrades, but a higher number like 50 would be enough to most of the people.
Of course there are people that don't ever has this issue as they have too many nominations pending, but this could change if the upgrades are no longer used automatically.
Goal: Keep those reviewers that spend a lot of time on Wayfarer as they get more upgrades to use later when they send more nominations.

Comments
Actually, I never understand why there is even a limit of available upgrades. Is Niantic hoping for even more free work by the community?
I would not make a limit, it's just useless, and in special while Covid 19, there are players who don't have the chance of going outside and submit for sure. Such people suffer from this limit even harder.
The option I would pick is save as many as you want
I set the 2nd option as 50 to avoid having too many options in the poll.
Having unlimited upgrades stored on one hand sounds good, and very few people might review so much that they are able to store over 50 upgrades without ever using them, but there might be arguments against that (for example imagine that they are storing that data using a byte, in order to change it to an int32 that can store millions they have to change existing code, structures, .... changing the limit from 10 to 50 doesn't require so many deep changes)
I would rather not store upgrades, and would store something akin to say, Wayfarer credits. Things that you can kind of redeem for other random things (such as maybe an appeal that you could use three upgrades' worth for either Niantic staff or the proposed "Wayfarer Community Advocates", or maybe redeem a bonus nomination [one-off, like an inventory on top of the rolling nominations] for two upgrades' worth) because I hate upgrades with a passion. Upgrading things will lead regular things like tennis courts and playgrounds for the most ludicrous of reasons and I would not like to bank these.
In actual fact, just as said in the Improving the system post, I often stop reviewing because I don't want to apply an upgrade.
But in the chance that such an inherent system won't change and if I really had to just store upgrades, then... 10 is fine enough.
(Duplicate deleted)
Looks like my post disappeared ?
I totally agree with @HaramDingo-ING. I didn't vote because I would have selected "no" but I'm aware that in some areas people need upgrades. I live in a rural **** area, submissions don't take too much time to be processed (3 weeks to 2 months) and upgrades usually lead to massive rejections (either it's considered a trail-path-natural-feature-generic-sign, either it's considered without safe pedestrian access, which makes no sense because all the area is a pedestrian but we don't have concrete sidewalks. Locals know that, they know it's safe, they know the history of places, etc.). So, I'm always anticipating the next upgrade, trying to slow down my reviewing so that my submissions are processed before the upgrade is applied, or riding my bicycle in the cities around in the hope of finding something solid to submit and upgrade). That's why I don't feel really concerned with the number of upgrades (of course that could change if the system changes), I just wish I could choose not to apply them. Sometimes I find a bunch of POIs to nominate and then I realize the upgrade is really close so I feel in a rush to find a solution (refraining from reviewing, or looking for a POI in a city but it's not that simple, in the cities the good stuff are already Wayspots ! And it takes times...).
**** = was censored but it meant "in the woods" so I don't know ?? 🤔