Is making notes worth it? (GCSE Maths)

In MY experience, making notes when revising for an exam has proven to be quite ineffective, PROVIDED you already have notes somewhere which you can refer to when revising. If you don't have any notes for a particular topic that may crop up, then making notes so you can refer back to them when attempting questions may be useful.

Many of my friends who achieved a 9 in Maths/A* in Further Maths only used the notes they made in the lesson (which must have been sufficient enough for them) and the rest of their revision was just doing past papers and practice questions repeatedly for all the individual topics.

That said, everyone is different, maybe your retention relies upon writing down notes, so I can't tell you whether or not to make any, only offer advice based on my own experience.

Good luck!