well, I'd say to spend more time on Language? cuz for language GCSE I think the only thing that can improve ur grade is to memorise all the vocab, It is obviously Easter now so probably don't memorise all of them but pick some very common vocabs that you can use everywhere, eg:
if there are always, often, usually, sometimes, barely, never, then I'll just pick 'often' and 'barely' to remember, I'll do around 30mins to remember certain numbers of vocab and come back to it later in the day again.
for the other subject I think ur grades are already good enough so probably spend more on papers instead of notes? like about 1-1.5 hours per subjects and 4 subjects per day?
for Art I think it's simply spending a lot of time to improve the quality and quantity of ur artworks so if u don't have enough time, just ignore it