That question came up to me, when recently working on one project I needed to restart my PC several times. And therefore, while I used 3-5 web apps I needed to log back in to each one of them again, after each restart. And I started wondering if privacy-wise that auto-clear feature is worth it or not? Has anyone maybe tested that?
So Firefox has tab sandbox isolation built in, but its cumbersome to use. When I started using waterfox they suggested a Mozilla add-on that made the feature more available. Have to go look at it, container something.
That being said, you can explicitly set URLs to sandbox groups, which is pretty handy when you want to keep cookies buy you don’t want them shared necessarily across sites.
Combined with noscript and ublock I have fine grain control of what I allow to run on sites and what cookies I’ll take.
So for sites I regularly visit I have it all preconfigured.
Then I just use a sandbox for random browsing.
Ticks all the boxes for me, without needing separate browsers for “everyday” tasks.