I've gotten so cheap I have figured out a way to reduce my exposures when using Polaroid 55 in tricky lighting or uncertain situations. This may not be new but I haven't seen it posted elsewhere.
Lets assume your light meter indicates an incident reading of 1/2 second at a chosen fstop rated for a print at ISO 50. For some reason you don't trust it and want to test to be sure. Below are two possible quick tests.
A) Assuming you think it might be under exposing your film: You will want to see -1 stop to +1 stop. Insert the film in the holder as normal and pull the envelope out as normal, then mark 1 inch intervals from the holder to the edge of the envelope. Change your shutter speed to 1 stop below your meter reading, in our example 1/4sec. Make an exposure. then slide the envelope to the first mark, and make another 1/4 sec exposure. Repeat this for 4 exposures. When you are done and process the print, you will have -1, 0 (meter), +1/2 and +1 stop exposures from your meter. (1/4 = -1, 2x1/4= Meter, 3x1/4=+1/2, 4x1/4= +1stop). Pick the best frame and use that for your final exposure. If the ideal stop is somewhere between two exposures then adjust your fstop accordingly.
B) Assuming you think you would prefer less exposure than your meter use 2 stops faster shutter (1/8th) and do the same 4 exposures as above. That will give you -2, -1, -1/2, and 0stop exposures to compare.
IF you do 6 exposures you can get +1/4th stop and +1/2 stop as well.
Notes: You can also use the exposure test before exposing your favorite film. Be sure to adjust for film speed differences. There may be slight differences in cumulative vs actual shutter speeds; two 1/4th sec exposures may not equal 1/2 second. Your shutter would need to be tested for this.
this may work with pack film backs too if you can move the darkslide back and forth.