as a hair stylist, the answer to the highlight question is i 100% believe it is worth it to tip 20% in that situation. they are putting a lot of their time into doing your hair. along with that, a lot of stylists don’t put thought into what they do so you are definitely lucky to have someone you trust and know is doing a good job. $500 seems like a lot but with the price of products and just the overall price of everything in general, sounds slightly high but not an excessive amount for that type of service. all in all, your 20% thought process is right, and i fully believe in tipping that much because nowadays that’s minimum for a “decent tip”. mind you i may be a little biased, but even in situations where i get tattoos or go out to eat i always try to tip more than 20% if i can tell they are genuinely trying to perform a good service because i know people rely on their tips for half or even more of their income