Sometimes waiting for all the utilities to be marked before starting the job can be a pain in the schedule. The wait time depends on their schedule mainly around a 72 hr window. So if you are a small contractor like me waiting can be a pain however on the other hand if you are a larger fence company then you have the luxury of scheduling in other jobs around the waiting period.
Now I can tell you if every fencing contractor calls for a locate every time they dig. Should they? I say that's up to them and the experienced digger. I mean come on if you see a gas meter, chances are that there is an underground pipe in line with the meter running out to the street. Now cable is a different story and can be very expensive repairing. Just as it is with any line that gets damaged caused from digging all can be very cumbersome and expensive. Not to mention just the shear headaches that come from the bureaucrats and politics that ensue the guilty party.
Yes I have had my experiences at either damaging or breaking a line from not having the job located. Even when I was a laborer I found several hidden lines buried. One time on a Saturday at a trailer park all the holes were dug and we were just dropping posts in the hole getting ready for cement when all of a sudden after I dropped the post in a hole a 4" geyser of water shoots up out of the hole and starts the flooding process. Now as I mentioned it was a Saturday and the grounds maintenance keeper was not on site that day so the rush to find someone who knows where all the shut off valves are located was frantic and the panic from some of the trailer residents was evident.
Calling for a locate is a free service and quite easy to do. Here in Oregon just call 811 with all of the information where the digging will take place and wha la in about 72 hrs depending on when you place your ticket request you will be digging your way to China or to the depth necessary for the work you need to accomplish.
Safety should always be a number one priority with any task and when it comes to digging calling for a locate is a safety precaution and should be implemented and exercised. If you don't call for a locate and happen to damage or even break a line I do hope that you have insurance to cover the cost of repairs and what ever other kind of liabilities are tacked on as a result from not calling first before you dig.
I am not going to sit here and tell you how to do your job because I am not the perfect call before you dig person either. I am just saying that it is a good idea to do so. I am not sure if it is a law as of yet, but who knows some day it just may become a law, there are sillier things that are a law then calling before you dig.
Be careful and use common sense, if the customer is wise to locating services use them, if you are in fear of legalities use the service, if you are unsure of witching sticks and your common judgement then by all means use the service. Represent your company with good standards, calling before you dig is just good quality customer service.