Wearing last aligner for 4 weeks?

I am on tray 14 of 17. I normally change them out weekly on Wednesday (which is tomorrow). However, my next appointment is not until a week after I'm done with my last tray. My next appointment after that (for the refinement trays) will be 3 weeks later. Therefore, I will be wearing my last tray for about a month. at the suggestion of my ortho, I will wear my last 3 trays for an extra day. But that still leaves me wearing my last tray for 3.5 weeks. In your experience, are the aligners durable enough to wear for that long? I make sure to clean them multiple times a day, so I don't think they'll get too ugly. I'm mostly just worried about them wearing down.