I prefer to do my own testing per advise on this forum. There are many benefits to that and I'll summarize some of them.
(1) I have confidence my results are accurate.
(2) I don't have to drive to the pool store.
(3) I don't have to endure the store clerk trying to sell me expensive chemicals that I don't need.
(4) I don't feel obligated to purchase at least "something" from them in return for the "free" testing they have performed for me.
This empowers me to save a lot of $$$ maintaining my pool and to keep the water sparkling at all times. I'm a happy camper...
In defense of my local "L" store, I've noticed they use the same Taylor kit and reagents that I use. For comparative purposes I've allowed them to test my water a number of times since I got my test kit about two years ago and they have always gotten virtually the same results I got. The kicker against them is their recommendations for chlorination and dealing with algae are much more costly than is necessary.