Well, anything 'Christmas-sy' should really be taken down outside by Epiphany. Wreaths, bows, etc. I have no objection to leaving outside lights up though. Inside Yeah, I like to leave the tree up. It's just so pretty.
My mother starts decorating in October and takes her window down after the Feast of the Epiphany. The lights are off on that day. They get removed soon after. She doesn't finish putting things away until February at the earliest because she has so much decorated and it takes time to put it all away. I think she would leave the big tree up longer, but once you start putting things away, there is no point. It's a real clutter.
I drove my wife crazy with the tree last year. It was decorated, undecorated, redecorated, undecorated and then decorated again. It's a 9 foot tree, too!
I couldn't get it to look right. The tree must be perfect. That is my mother coming out roflmao.