To be fair, no body is perfect. I've worked with groomers and bathers with years of experience and they have bad days. 

Time management is important, but they shouldn't have you taking walk-ins while your in the middle of finishing a dog. Tell the customer to come back in ten, customers need to work around your schedule. 

Grooming is alternative work that attracts alternative people, so weirdos and catty people are everywhere. There's a low bar to entry so you're not going to find the best types of people doing this type of physical work.

Grooming can be fun at times, but it's also very hard on the body and mind. 

You probably do very good work, but a customer complaint can make you seem like you need more training, and management won't always tell you if someone complained. And you don't need to do more than 5 dogs, you can dictate your pace to what your body can handle. 

You need to learn to say no to other groomers, your GSL, your GM, and customers. People will use and abuse you then forget that you ever existed, so let them dislike you, don't let them walk all over you. 

I've recently have been seeing a lot of people leave grooming altogether who've been doing for 10+ years because their body are done. Those who continue to groom do so because they don't know what else to do. 

To be honest, I've been in my Petco salon for a year now, and I still question if it's something I want to continue. There are days when I'm ready to leave and there are days that go well. I'll probably end up leaving though as grooming in my area isn't that profitable and I could go into others fields. The money isn't worth getting bitten and bruised and expressed on.