Looking at timelines helped me, so I wanted to offer mine. Briefly, my adult US passport expired over five years ago, so I needed to renew in person. This was done at a US post office. I was a bit concerned about the old, expired passport taking a while to return as it seemed to be longer than others. Several family members including minors are also in process, as well as some overseas renewals if anyone would like me to post those as well.
24 March - Appt at Post Office - submitted application, old PP, photo, payment
30 March - Status changed to “in process”. Per the ID number, it was in New Orleans
31 March - Received an email from @state.gov saying status is “in process”
15 April - Status changed to “approved” (no email notification)
15 April - Received an email from USPS that said PP was mailed, due 20 April
17 April - Passport book arrived (priority mail, with tracking, from Arkansas)
20 April - Passport card arrived (first class mail, no tracking)
20 April - Status changed to “supporting documents mailed” (no email notification)
25 April - Email (@state.gov) received saying supporting documents mailed on the 20th
1 May - Old PP returned via first class mail (almost 2wks later).
So almost four weeks from application to new PP and almost 6 weeks for documents to be returned. Hope this helps!