Ok
2 things really. But I am sure people can think of more.
Spelling tests - if you're a good speller, you'll probably not need to practise much and you'll probably get most of them right.
Do spelling tests improve your spellings? Why do people who need to learn them get them right in the test but get them wrong in their normal writing?
Homework - does it help you learn? Remember stuff. Help you improve. Or is it done because that's the way it's always been so people expect it?
I don't think there's any evidence to support the educational effectiveness of spelling tests or homework. Good teaching and identification of reading / spelling issues helps you learn to spell.
But we like tradition, not evidence, don't we 