I've been sporadically working on an App called "NumberLogger", which lets you log numbers quickly.

Say for example you're recording your weight daily. I used to open google sheets on my phone, go to the correct sheet, insert a row at the top, tap on the first element, and enter the number and the date. It took a while to do and had some fiddly actions as part of it, but it did let me record in a way that could show me a graph.

In my app, when it opens you see a keypad on screen and the last couple of entries. You can tap on an entry to fill the current entry with the same number, you can type the number, and you can use "+" and "-" to modify the number (by the last significant digit).

So my app idea is a part of NumberLogger. There are some things that you want to log for a particular day and you don't care about the time of day that you log them. So I'm going to add a configurable parameter for the time-span resolution. It can be set to a number and a unit - so, second/minute/hour/day/week/month/year, and the number is the count of that unit.

With resolution set to 2 weeks, any number you enter in that two week period will still be recorded, but will be treated as a single number for the purposes of graphing. And when graphing you can specify the start of each time period.

For my daily weight recordings I always weigh myself at the same time but don't record the value until later. The weight recording is intended to cover a particular day; the hour/minute/second aren't important and shouldn't contribute to the graph.