I've come to understand that when something is a keeper, it is pretty clear pretty quickly and without hand-wringing. If I start to obsess too long the answer is there -- I just have to accept it.
If I am obsessing for too long about whether or not to buy, I should pass.
If I am obsessing for too long about whether or not to return, I should return.
Simply put, obsessing in any way about keeping an item means it's not right for me.
Sometimes it takes me a while to accept the obvious, though. I experienced so much internal back and forth on the slim bootcuts I recently tried on, and only when talking to Suz in Boston did it become clear that I needed to return them. I was hand-wringing over the length of the bootcuts and whether or not I would have to hem them to wear them, etc. etc., and whether or not I wanted to wear heels on a daily basis to justify the jeans, and she rightly noted that I can satisfy the bootcut itch -- if it really exists -- quite inexpensively through thrifting or ebay. I don't even know if I will do that, but I knew instantly when she said it that I needed to relieve myself of the inner drama. So out they went. Whew - it felt good!
On the other hand, I was committed pretty quickly to the Reiss navy tuxedo jacket in Boston even though it is definitely one of the most expensive things in my closet (maybe the most). I did ask Suz and Angie for their opinions, but it was a pretty fast purchase. I just knew. Got it home Saturday, tags off and wearing today. No drama, no regrets.