Thanks for all these tips, Todd! Particularly the group tabs one.
It might actually save my old 2013 Macbook Pro from dying a battery death because I don't turn it off - just let it sleep with all of my favourite tabs and programs open.
Then again, when it does die, it'll be high time to get a new one anyway.
For those who can't concentrate with music (being a musician I'm always on the lookout for nifty phrasing), I would recommend Noisli.
It plays background noise to your liking e.g. nature sounds, white noise, cafe - plus you can mix and match them to create favourite combinations!