So I don't have a torque wrench. Tutorial recommended about 40NM for cassette on the thinkrider. How vital is it to be accurate on that? Can I get away with just getting it "tight enough"?
You should 100pc get a torque wrench if you have carbon bikes, on AliExpress they cost 20-25 Euro shipped and they're wonderful.
40nm is tight AF, it's far beyond tight enough. So for sure, just be brutal with it and voilà, you don't need a torque wrench for that.