I find weekends are just more hit and miss than weekdays, which in any one area I can usually bet on a fairly accurate estimation of how the day will go (bookings at lunch time, quiet spell, a few after work hours and maybe one late one if I work it) but weekends never seem to establish anything like a pattern IMO, I guess because clients are not behaving in more uniform ways as they are on weekdays (obviously not everyone works 9-5 mon-fri but I find most my clients do roughly at least).
That said I don't necessarily find them less busy but I get more young guys, international guys - basically guys less likely to have childcare responsibilities etc I find these sorts tend to be less likely to book in advance so I wouldn't worry too much about not having advance bookings. The other I used to notice is, it often 'kicks off later', as in I find bookings start to roll in after lunch. Maybe because of hangovers/lie ins etc