I have tried working all different combinations of days and times. I have a structure now but that's only because I like to have a work routine so I can plan my life accordingly.
Mondays are always consistently busy for me between 9am and 6pm
Tuesdays are less so, but still worth working 9am - 6pm.
Wednesdays are dead.
Thursdays used to be one of my busiest days but now it is the last day to get fully booked and I regularly have to accept bookings on the day. I used to do 10am - 10pm but have now cut it back to 10am - 6pm because I just wasn't really getting that many evening bookings.
Fridays were my ultimate busiest day for so long, then it went through a period of being really quiet with other days taking the lead. I used to work 10am - 10pm, then cut it back to 6pm when it was quieter, now that work seems to have picked up, I advertise late again.
Saturdays were always hit or miss, especially until 3pmish. I work the odd Saturday late afternoon to 9pm / 10pm. I'll do ok ut not as busy as other days.
Sundays are good from 12pm / 1pm if you dont mind seeing hungover people.
To sum up, where I am based, I will get work any day if I don't mind sitting about for hours in between bookings. But I hate this, so I now zone in on the days I will be fully booked so I can show up, do my bookings then leave and go home for dinner and enjoy my evening. Tues, Wed and Sag being the slowest days for me, the remainder being consistently good.