Sync strategy is too aggressive for battery powered devices

[otherstew]

I realize that this was dismissed in #45, but I take issue with that response because in my experience the battery drain is extreme.

While writing, this app uses power >2x as fast as streaming video (same network, same display brightness, AMOLED display with SN in dark mode, video with phone speaker audio). Using this app for 20 minutes chews through 10-15% on my phone (Galaxy S10e) depending on the quality of the network connection, and the device gets noticeably warmer after the first several minutes. Similar story on a tablet.

If I temporarily disable the network connection for the app while writing, then the drain drops to around 2% and there is no warming.

It seems like the sync/idle timer (250ms when signed in/online?) is so short that the sync strategy ends up approximating continuous sync-as-you-type, which I think is excessive for an app with no live collaboration and where it seems like the intended sync strategy is sync-on-input-idle. Since user typing speed is a factor for how often sync is triggered, how about making the sync delay timer configurable as was suggested in the previous issue (maybe even just a few levels, e.g. default=250ms, slow=1sec, reallyslow=15sec)?

My ideal solution would actually be to allow choosing between the current auto-save strategy and save-on-close-note, but maybe there are philosophical incompatibilities with that suggestion.

Otherwise this app ticks all the boxes and I'd almost certainly pay for a subscription if I could use this app without having to recharge my phone during the day.