Different image sizes!

[Pippis]

Fellow comrades!

Please answer me this? What kind of size do you use when drawing different artworks? For example, using Photoshop, doing a matte painting in one size and a portrait in another size? Hope you understand my question.

Have a wonderful day!

[J Wilson]

Just a little bigger than it needs to be.

[Flake]

If in doubt go big.

Shrinking an image is easy, enlarging it is not.

[Pippis]

Thanks for the reply, and I already paint by that rule.
What I wondered more, though not apparent with my language, is how big different types of paintings are? 1600x1000pix 800x600pix, A3, A4 etc.. Matte paintings versus portraits and other. Both digital and "manual", thanks!