In my business, I find a common factor of Fridays. I believe it is because attorneys and "legal service" companies want to clean up their pending workload before weeks end. So, more often than not, there is a Friday rush of papers to be served.
I even usually wait to go do Friday evening serves until after 5pm, to make sure that I will be able to catch all of thos last minute papers. The problem is, some find ways to even get them to me after that. Many of the people that I serve for email me th documents to be served. On company, I went out on Friday and returned after 7pm, and still had no new documents. When I checked on Saturday, there were 10 new papers to be served. I was originally planning on a "slow" Saturday, but that had changed my plans.
Yes, I could have waited until Monday to start service, but I really do not like having a lot of pending work myself, but that applies to any day - not just Fridays.
I have learned to expect the rush of papers, but sometimes they still find ways to surprise me.