I'm curious, what do you use it for?
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For me, I often get to Friday afternoon and realise I haven't recorded my time all week.
Supposed to be billing clients for tasks.
Screen caps every 15 minutes helps me see what I was doing
that's exactly what I'd like to use it for, although using shareX for this seems a little inconvenient? I assume it wouldn't have any sort of timeline feature to go along with it? will it start the auto capture automatically when my laptop is powered on or even comes out of standby?
Would a timeline really provide much benefit over viewing screenshots in a folder?
This one has a calendar:
https://m.majorgeeks.com/files/details/auto_screen_capture.html
https://activitywatch.net/ doesn't take screenshots, But depending on what you're using it may accurately accurately record what you're doing in a different way.
This is another tool that doesn't exactly do what you're asking for but may also be useful. https://wiki.gnome.org/Apps/ActivityJournal
Sharex auto capture?
You could build something in Macrodroid/Automate/Tasker. Someone may have already made one.