Polaroid is not my recording medium of choice, but without a 4x5 darkroom, Polaroid is a practical choice, and scan. Most of my pictures on PinPLUS side of www.huecandela.com are Polaroid. Have found that Polaroid Polapan 54 for sunlight and Polaroid Polapan 72 for overcast, full shade, and flash for macro pinhole pictures works well for direct pinhole picture prints.
After Three shoots/test of the below Polarid, my formula for simple recopicity failure is below. Polaroid Polapan 54 seconds ^1.16 for 1 sec use ((2 seconds)^1.16)/2 Polaroid Polapan 72 seconds ^ 1.24 for 1 sec use ((2 seconds)^1.24)/2 or 1sec 1.5sec 2sec 3sec 4sec Polaroid Polapan 54 1.1 1.6 2.2 3.6 5.6 Polaroid Polapan 72 1.1 1.7 2.4 3.9 5.6 6sec 8sec 12sec 16sec 24sec Polaroid Polapan 54 8.0 11.2 17.9 24.9 39.9 Polaroid Polapan 72 9.2 13.2 21.8 31.1 51.5 Paul Prober