Lately I’ve been updating on Monday, Wednesday, and sometimes Friday and/or Saturday (this week is a rarity!). If you’re still following this comic by loading the page directly (and my tracking stats say that’s most of you), you should be aware that I do vary updates from time to time, and if you’re specifically checking only on weekdays, keep in mind that I often post stuff on Saturday and sometimes Sunday. You can always look at the calendar in the corner of nearly every page to see when posts were made (or are scheduled to be made).
Of course, you can always subscribe via RSS or LiveJournal and always see the comic the same day it gets posted, and not have to worry about me posting on multiple days between the times you checked. You also won’t miss news posts, since I know these are so incredibly interesting to read.
For what it’s worth, I try to keep my update slots consistent, when they do happen; Monday and Wednesday will usually be Unity, Saturday will usually be either a sketchbook entry or Womble, and Friday is wide open (Journal comics, fanart, a third Unity, etc.).