There are splashbacks that are 3 tiles high running along 1 wall and there are splashbacks that are more involved as I am sure you are aware. To fix over 400 tiles cutting round sockets and wall units, grout and Silicon in 5 to 6 hours, is IMO not feasible.
if you can work that fast and to a
standard that is acceptable to a cusomer then you should be charging more money as you will have built a reputaion.
I personally, am only 1 year into the trade and I am not embarrassed to say so. I, personally could not do that particular job in 5 to 6 hours, not would I want to. My work is coming through now via referrals and my customers are happy with what I quote and with the standard of my work.
I am laying a marble floor in a kitchen 2 weeks time. 6.7m2 floor needs prepping and levelling, customer came to me via referral and I will be charging in the region of £850 for the privilege.
Maybe I am in the right job after all. What do you think?