Hmm good question Anne.
I don't think I could ever wear a denim jacket with denim pants...so I would go cold before committing that crime.
I will fudge PPL sometimes. I try to keep it to no more than a 1/2 inch in either direction--and I bet most non YLF people don't notice.
Today I was faced with this choice. Wear a white cami that is a little to high in the neck with my white Bratique shirt (the top of the cami showed) or skip the white cami. Granted, I was planning on wearing a grey jacket, but knew if I took the grey jacket off, I'd be wearing a white shirt w/out a white base layer. I chose to wear the cami and let a bit of it peek out the top. This just reminds me that I need to get a second white low neck cami and only wear it with this top. My other one was in the laundry.
I have held off wearing things until I have the right piece to go with it, or until it was altered properly. But I've also rolled up jacket sleeves so I could wear something before the arms were shortened.