I reentered the US over 20 times while on AP, no issues. The only realistic risk of not being admitted is if the I-485 was found to be abandoned while outside the country, for example by missing biometrics/interview appointment or not responding to an RFE in a timely manner. Being out for max 2-3 weeks should be no issue at all.
You just need to be aware of the likelihood of ending up in secondary inspection every time you reenter on AP - if you're flying with domestic connections ensure you book flights with sufficient stopover. Personally I would not do anything less than 3 hours if traveling on AP with checked-in luggage.