I've realised I've tended to use full 24bit bitdepth for theme backdrops/icons, as it makes manipulating them in paint programs easier.
Is it better to down-convert them to 8-bit in the end? Doesn't seem to make any difference on my player, but is memory usage something to worry about for themes?
(Still have a lot of themes I could upload, but its annoying to keep finding tiny bugs in them after uploading them. Feels daft to upload a new version because one thing is one pixel out of alignment.)