Microfilm rental allows for film to remain at the library for a period of 10 weeks before being returned. Where most researchers charge for travel time, I do not. I use resources both in Bakersfield, CA, but also in many cities in Southern California, such as Burbank, Los Angeles, San Diego, etc. A normal round trip from Bakersfield to Los Angeles is about 220 miles and with traffic about 5 hours of time. I only do what the customer wants and we can stop or proceed after each 5 hour segment is comleted.
Some people even space out their projects over lengthy periods of time to work within their budgets.