As for switching between sessions — it's the hierarchy that's lost on tabs.

in 1.17 I get basically a three-level hierarchy: project -> workspace -> session

I could say I rarely use more than one session per workspace (not including subagents), but switching between projects as totally separate contexts works good.

Tabs on the other hand are less organized, I can see them being fine for sessions in one project (although sidebar is more ergonomical on both desktop and mobile)

Keep in mind that this is coming from someone who has a live browser tab counter website: https://tabs.evtn.me/