I do industrials and that is a huge pita. I have to either drive it about 8 hours away for service, drop off and do it again 6 weeks later or pay for a tech to come into my shop, with a $250 on site fee (and min of $300 service fee) unless I can wait until they travel into my area twice a year (then I can get the work for hourly cost...I am on the route).
Probably why my industrial machine has been down for 2 months. I usually do the work on it, but it takes me a while and currently my needle bar needs adjusting. I just haven't had time.
On regular machines...I have a business I can go to an hour away and will service all my domestics including my treadles, but I don't buy anything expensive from them: I can't get help in store to look at machines, and I don't embroidery or need a TOL regular machine and they don't sell industrials. I can go 3 hours away and buy an industrial but they don't service them...and for the cost I can buy a new machine and get it shipped for less then they sell their used ones.
Not sure about any etiquette in it anymore...used to be you bought a machine, serviced it once a year and traded up every 5 or so and maybe buy a vacuum or bags in there, too. Now my neck of the woods, they don't have stock, don't want to help you get the machine you want and in my experience try to convince you that you need 10K plus machines...and when you don't want to look at long arms or embroidery machines gesture to the plastic wonder machines boxed along the wall and walk off...which you can't test because the only machines you can test takes a 2 week later appointment and are the long arms/embroidery machines. But they do a lot of mail order business, so I can get domestic machines at a fair price.