I have personally changed approximately 60,000 watch batteries. I have a huge amount of experience which I will deploy on your watch and do a perfect job every single time.
The truth is most battery watch issues arise from the batteries being installed in a careless clumsy fashion, with finger prints and bits of dirt being put inside. Every week I see watches that are not working because they have been plastered with fingerprints.
My battery change is the exact opposite, I always clean the battery contacts to remove mess/fingerprints, install clean batteries, and clean the cases to ensure no dirt is finding its way inside. I will remove dirt where I find it, and do what is best for the watch.
I give every watch the same quality job, checking for problems, lubricating buttons and seals where possible. And you will get to see the photos of your watch when collecting so you can see exactly what I found and what I did.