For DAAD, it is not necessary to create a standard colour palette for all screens. In this particular case, DAAD requires a resolution of 320×200 px with 32 colours per image. However, some games use different graphics modes, so 32 colours is by no means an absolute rule. It depends very much on the extent to which you wish to maintain compatibility with older Amiga models.
In classic Amiga 500 games, you will very often encounter:
320 × 200 / 320 × 256 px – the most common low resolution 32 colours simultaneously – the standard ECS/OCS mode for games sometimes 16 colours, or even fewer 64 colours in EHB (Extra Half-Brite) mode HAM modes are used less frequently in standard games.
Personally, I prefer a resolution of 320×200 px with 32 colours, as it makes it easier to edit pixels in an image.