Does following the spec give you a better chance?

Not really, for example the AQA chemistry specification summaries ionisation energies in this:

"know the electron configurations of atoms and ions up to
Z = 36 in terms of levels and sub-levels (orbitals) s, p and d
know the meaning of the term ionisation energy.
understand how ionisation energies in Period 3
(Na – Ar) and in Group 2 (Be – Ba) give evidence for electron
arrangement in sub-levels and in levels"

...which is ridiculously useless and a deathtrap for someone expecting to do well just by memorising this - you need to know stuff beyond the specification and be prepare to apply things without being officially told to by the exam board.

Yes but how do i know what to 'learn beyond the spec'?

Past papers. Millions of them. If it isn't on the spec, and it hasn't appeared in any of the past papers it's probably safe to ignore.

You say millions, but aqa only have 8-10 for chem