jmow wrote:
I'm sorry @EauRouge, but this is not a quality answer. On a 128 GB disk like mine, there are only a couple of files that you can remove, the others you need, hence the disk space issue. It is simply not possible for Mojave to require that space needs to be freed every few minutes. I used to have as little as 3-5 GB free space until Mojave and that was fine (from a user point of view; I understand this may have stressed the SSD, but this is my SSD, it should not decide for me). Now I manage to free up to 10 GB, but this is still not enough for Mojave. Well, I'd say either this is a bug or an over zealous restriction in much the same way than slowing down iPhones was without warning the user when the battery was getting old. It seems APFS does a better job at managing free space on iOS than it does on macOS.
Well, you must remember that your disk/SSD is more than just storage space: it is the component that makes your device run. Every time you do anything at all, it needs to find space to write and/or find the file to read, so it works better if you maintain more continuous empty space - especially with SSDs which are written to in blocks. If you do not maintain enough space for it to work properly, you will get kernel panics, beachballs, and finally, a corrupted disk.
So, it’s your decision of course. FWIW, I would never buy anything with only a 128 GB disk and I always keep about 50% empty. The only thing with that small a drive is my iPad Pro which I use for reading, photography (the pics are moved off), and projecting TV shows on my TV.