I'm sure most people find doing the end of month accounts a pain, but I have made mine as easy as possible. First of all I don't have a large number of clients, but I do regular work for the clients that I do have.
My first step is to log all my time using minutedock. I can even log unbillable time or log time against tickets in Zendesk. I do work for some NGO's and I don't like to bill them for all my time, but I like to show it on my invoices. I bill most of my clients monthly and I use minutedock to accrue the time and create a single end of month invoice.
At the end of the month, I simply use minutedock to create the invoices directly in Xero. I then login to Xero and email the invoices to my clients. This is a simple matter or sorting the Unpaid invoices by Sent status and selecting the unset invoices and clicking the email button. Previously I used to create a draft invoice in Xero and just add time to this, but I found this a bit cumbersome.
minutedock makes it so much easier to not only create invoices, but to capture (nearly all!!!) of my time and Xero is just a fantastic piece of software.