Get into a group with about a half dozen other people and agree to share all of your leftover data, in 100MB increments, just before your billing cycle rolls, each month.
Have everyone change the first and last name on their account to a naming convention that conveys rollover date, priority, and identifying information.
The day that your data is supposed to roll, simply go into your one account and give away your data to five people in your group who just rolled their month. That will give the donated data the longest "shelf life".
By doing this you only have to log into each account once, just before it rolls, and your devices will automatically fill up as everyone else's devices roll.
26-1 Chelle SIM means "rolls on the 26th, is a priority 1 (I really want data on this device), and it's one of Chelle's SIMs".
04-2 Chelle MiFi 500 means "rolls on the 4th, lower priority, and it's one of Chelle's hotspots that she apparently doesn't use as much".
13-DoNotSend Chelle SIM means "strictly a donor SIM and any data sent to it would be wasted, so please don't send any data to this account".
I'm in this arrangement with a pretty good size group of people and my devices tend to max out pretty quickly. I also end up giving away even more than I use.
If you wanted to put such a group together you could probably organize it, here, and share FP email addresses using PMs, here, as well.
It started out with just me and one person, from RingPlus, and we came up with the system, together, to make sure that we didn't accidentally donate data to a device that was just about to rollover. We just used it between us, for awhile.
As we each onboarded more people we all friended each other and broadened the group.
I've posted our system in several places and have started to notice more people using the system. I think it takes some of the randomness out and improves the efficiency of the data sharing process.
Until reading your novel idea, the thought that I had was to open five LTE SIM FP accounts (for $0.99 one time cost each to open) and transfer each month 100 MB from each of those five FP accounts to my primary FP account.
That's a cool thought worthy of consideration. Though I'm thinking that the idea with the SIMs also gives you five spare SIMs you can pop into your device, if necessary, with 700 MB/month each. All only costing 99 cents each (once).
@Chelle In the FP group system you outlined you suggested organizing about half a dozen people in addition to oneself in the group. You also mentioned you have a pretty good size group of people. Is there an optimal size for this type of arrangement? Is it the bigger the better (as you seem to have a larger size group)?
If group members always donate their about to expire data to the accounts with the most recently begun billing cycle (with the highest priority), effectively you'll probably end up with each donor always donating to the same set of recepient accounts each month, based on the billing cycles. As such, is there not the risk certain accounts that happen to not have the "right" cycle starting date could get very few to no data donations every month?
Also, what other places have you posted your system to?
I suppose it's possible that some devices wouldn't benefit as much as others but, in our group, we actually have the opposite problem-- we tend to have more data to give away than there are parking spots to put it.
I usually end up sharing some data with strangers, and I give first preference to people who include a rollover date in their name.
As for the groups I've shared the system with, I've shared it in the RingPlus forum and in a few Facebook groups that I'm in, with friends.
If your bill date is the 14th that means that the last day of your billing cycle is the 13th. So I would name that account 13-(something) and know that I had to make donations on the 13th (since that's the day that the account will say 0 days left).
And you could safely donate to anything 12 or earlier because it would have fresh data on the 13th.