Maybe the issue is that you have been overlooking the finer points of the assignments. Timing it out:
Mystery Shop: Pump gas, get a receipt. Walk the station, checking shelves, coolers, cleanliness, check the bathroom. Purchase item, do customer service at the counter. Return to the car, do beginning paperwork. = 10-15 minutes.
Reveal: Walk back inside, present LOA, Start taking your photos, of the employee, counter, bathroom, then out to the pumps. That is another 15-20 minutes.
Are you catching the dirty bathrooms, rusty MID, pumps, coolers? Or are all your reports the same status quo?
The minimum per station is 30-45 min, and that doesn't include the filing of the report.
I usually take 45-hour per station and then another 30 min to file. And then consider the closest station to my home is 14 miles. Maybe I need to go where you are so I can do 20 a day. I usually have 30-45 minute drives between locations.
Shopping Southern Georgia, Valdosta, Waycross, Quitman, Thomasville and North Central Florida I-10 & I-75.