Any where I have worked 45 minutes top and that included curling iron. I can do a wash and set in 45 minutes with a tease. I worked with someone who took an hour to do a cut and blow dry and her clients complained. Not everyone has an hour to sit in a salon. I know I don't. I can do most of my clients in 20 to 30 minutes unless their hair is very thick even at that 45 minutes tops.
I worked in one salon that booked you ever 15 minutes no matter what service you were doing on each person. I really didn't like that at all....So I opened my own salon 20 years ago and do not do that ever.
Before this question can REALLY be answered one must first ask the question... How much are you charging? 'cuz it matters. You can not separate one answer from the other.
I would even go farther to suggest that the first question to ask is... "what am I worth per hour, day, week, month, year?" Once you have established that value you can work backwards.
Your value will determine the price (considering your speed).
The price will determine the nature of your customer service.
Your target level of service will determine your timing.
And ultimately your clients will determine if your formula works.