How much is your time worth?
On the aforementioned 40 minute drive for two recessed cans, ask a few pertinent questions first, like:
How high up?
What is the ceiling made from?
Is there any furniture/staircases in the way?
Is the ceiling flat or sloped?
Is there overhead access?
Give a price over the phone. Even if you dont make a great profit on it, you've saved a 40 minute drive there, a 15-30 minute estimate, and a 40 minute drive back, a solid 2 hours labor and gas. If you dont get the job, no big loss right? If you get every estimate, your prices are probably too low.
After you do enough 'two can light' installs, you will be able to price over the phone or know off the top of your head how much time it takes and what materials will cost.
You dont have to say no. Just price the job based on worst case (takes an hour to get there, 3 to do the job, hour to get back). If your time is worth $125/hr, that's $525 plus materials, which would be ~$60 for two average recessed lights. If it's a ten minute drive and you can do it in two hours, then go by that.
We have a few places around here that just getting thru the contractor gate at 7:30-8:30AM can take almost half an hour. Yes, you bill for that. I didn't choose to own a home in a gated community and have Security Sam at the guard gate checking all credentials and what not like I'm driving onto Camp Peary. I didn't buy a house with 20' ceilings in the living room. If your customer did, they get to pay for those luxuries all over again when they want 'two can lights'.
There's not an EC in my area that would come here and give an estimate (free or otherwise) on a panel change at this place. Most will shoot a worst case (high) estimate at you over the phone. Free estimates for small jobs (4 hours or less) is largely a waste of time imho. You can always go high and give the customer a cheaper/lesser bill, but driving 2 hours to estimate a 2-3 hour job is not profitable imo.