I think Otto did a lot of the trips on the weekends and combined longer trips with holidays and days off. I took a handful of dates on the photo captions from the Sundance Otto Perry Pilgrimage book and entered them into an online perpetual calendar. The result was that most were on the weekends, holiday or Friday. I think he just lived to make these trips which from a cursory review appear to take place about once a month at least. The photo collection indexes sold by the DPL have dates for every picture he took. If someone could get this file as a database or spreadsheet file and then resort it by date I think you could get a idea of where he went on what date.