logwatch reports are a big help here.
I have an old Lenovo R61i that was fitted with a 128 GB Sandisk SSD when its original 120GB HDD died.
These days it mostly just runs protein folding software. Apart from that, there's a weekly rsync backup followed by a Fedora update, so this workload is making what I'd call low use of the SSD. The weekly smartd report shows that the SSD has been active 1-2 hours per week, confirming low usage.
Yet the weekly fstrim run usually reports its added a little over 1GB of storage space to the free blocks list. To me that shows that the weekly fstrim run is worthwhile, but running it more frequently is probably not worth the effort of retiming the cron job to run it more frequently.