I made a 6+ hour film ('Offshoots') that was too big to deal with. I decided to speed it up to greatly reduce playtime and was looking for the sweet spot. Here is a test film ('Time Studies') I made to see the range of playback speeds that I could use. 'Time Studies' covers regular speed up to 1000% faster in increments of 100%.
The test sample I used was pulled from 'Disciples of Androgyne' which is part 6 of 'Genderqueer'...a 65min film I made on the gender busting revolution. ( I will distribute 'Genderqueer' in a fast speed option as well as normal speed.)
These films are made under the auspices of 'fair use' for non-commercial, educational, editorial and historical purposes.