Advice on managing Briefcase storage on my hard drive

1. What is the problem? Be very detailed.
I've been using ODK for a few years now and my Briefcase is overflowing! I'm looking for advice on how people manage Briefcase storage on their local drives when collecting lots of data.

I have tried different strategies, such as separate Briefcase folders every year or so, and archiving the old ones. But effectively I end up with 3 sets of data on my hard drives... The ODK folders from my mobile devices (I tend to copy the instances into a single repository), the Briefcase storage, and then the exported data. Because we use a lot of images in our work, this space soon Aggregates (sorry for the pun!). So my Central question (oops!), is how can I safely reduce the duplication or simply archive stuff so that my exports relate to the current work (I have some standard forms that I use for different projects, so I can end up with an export which includes other data and I then need to delete irrelevant records / media. Which is a whole other potential function of Briefcase!

The docs are great for how to use Briefcase but there is a big hole which appears to assume you have infinite storage...

And when you dig into Briefcase (as I have naughtily done from time to time) there are "here be dragons" warnings. I have deleted folders and got away with it, but I'm wary about making things unstable by missing a folder or deleting the wrong set...

I guess it would be nice to be able to look in my briefcase and give it a bit of a spring clean, throw out all the festering sandwiches, post-it notes and broken pens! At the moment I just keep ramming stuff inside and hoping that I can shut the catch again.

2. What app or server are you using and on what device and operating system? Include version numbers.
Briefcase versions 1.6 to 1.17.3; I don't tend to use Aggregate or Central as the ongoing costs are not worthwhile, sometimes use Google Sheets, but there are issues still to be resolved there, mainly relating to images.

3. What you have you tried to fix the problem?
As above I've used different storage locations, and furkled around Briefcase folders...

4. What steps can we take to reproduce the problem?
Collect a whole load of data, collate it through Briefcase and see your hard drive fill up!

5. Anything else we should know or have? If you have a test form or screenshots or logs, attach below.

Perhaps we've been in Covi-19 lockdown in Scotland for long enough for me to get this desperate to want to sort through my briefcase! And unlikely to be let out again very quickly...