So I have about 200 tabs open usually. Is this a bad habit? I don't know, I just have different areas of interest and they just seem to accumulate.
Anyhow, I tried all the 'tab management' add-ons available, and this is the only one that works and made sense to me. I have about eight different groups, and navigation is simple.
User Tip: when you're on the 'Manage Groups' page, if you copy the web address, and then paste it in Firefox Settings > Home > Homepage, under 'Custom URL', then when you click on the Home button it brings you to the Manage Groups page. That is what make it work so well.
There was another tab management add-on which I really wanted to work, Tab Stash, but couldn't understand it, found it unintuitive (gonna write to the Dev), so this one wins!
Fantastic, many thanks Dev!

One of the good alternatives to Vivaldi's tab stack feature.

Excellent replacement for the old Panorama. The only... doubt is that last update was about a year ago. Is it still supported?

Very nice for working with many projects.

A must have if you like to organise your stuff.

boosts productivity. awesome tool. thanks a lot.

My productivity has improved so much with being able to have different tab groups for work, personal, research, volunteer work, etc! Great way to get in the zone and not be distracted by other parts of your life.
I have had it crash a few times, but when I close firefox and reopen it, all my tabs are still there so it's not a big deal. Be aware that it makes backups in your Downloads directory (starting with STG); you can delete the old ones at any time or disable this in settings.

Takes a bit of learning to figure out, but once you're comfortable using it, it's great! Love that it hides the tab group you're not using: less temptation to switch tasks.