I play it by ear. Depends on the child and the weather. A couple weeks ago it was cold enough for jackets but nothing life threatening. A 4 yo didn't want to wear his coat. Whatever, learn the hard way than he survived and we were outside for awhile ( at mickyc's actually lol) he's worn his jacket every day it's been sent since haha.

Kids have limited choices in their lives and I like to choose my battles. If it's not going to seriously harm them, than I'm all about them making a choice/decision for themself. They have to learn how IMO. Obviousl, if their choice is really not a good one than I'd step in though.