Yup. This covers "forgetful players", but it also helps me: a DM with ADHD that can get very lost in "meatspace" ("which of these four monsters that look exactly the same took 40 damage, again?" or "I am sure I had that monster token here somewhere...")

So I make tokens with pictures for the creatures on the top and space on the bottom to scribble the damage with dry-erase marker. Really helps.

Also: adding up is much faster than subtracting damage

Really recommend that method for anybody that wants to try and speed up combat