By the rules, you're not allowed to do that, but no one really listens to that rule and does it anyway.

without the letters up there it has proven difficult if not impossible to guess certain words. Especially when there are so many similar words like post, mail, letter, envelope or mail box, post box, mail slot, the list goes on.
However there has to be a line drawn somewhere. Breaking a word up into a couple of words like car-go is fine but drawing cat, apple, rabbit, grapes and orange is silly and pardon the pun, fruitless.
Think of the word first can you draw a drawbridge?- if so draw it, drawing a picture of someone drawing and a bridge is harder, isn't it? I know i've done it! Hourglass-LOL- a clock then a glass, time wine, clock drink oh geez why didn't I draw hourglass????
I hope this helps