I live in the country and some of my clients may need to be transported to a park of some kind or will want an extended walking time.
I have folks book two 30 minute walks if they want an hour. I have to transport pets sometimes and the clock starts when I pick up the dog so if I have to drive 5 minutes each way then unfortunately that is only 20 minutes at the park. Depending how busy you are or if you are able to pick up multiple dogs and walk them all at once you may choose not to charge for drive time, but I am so busy and booked that I can't consistently offer free 15-20 minutes to every client though I sometimes do for ones that take good care of me.