For what it’s worth, my son took Calc AB in high school last year and did well on the AP exam. He is taking CalcBC now and will be taking the AP test. We had heard the same thing as the OP that it may be wise to retake all required Calc classes in College and not use AP credit. The schools and engineering program he wants to go to require 3 Calc classes, 4 credits each, and then several other higher math classes. We visited one college recently and he asked to sit in on their Calc 1 class. He was familiar with what they were studying, felt his High school Calc AB covered it and has decided use his 4 AP credits for CalcAB and as a freshman enroll in the Calc 2 class. A couple of the students he talked to also recommend reviewing Calc via Khan academy or other method over the summer before freshman year and said they also enrolled directly I to the second Calc class, it was work, it they did well and were happy with the decision to not take (and pay for!) the Calc 1 class.