Like the others have said, Saturday auctions tend to be very different from weekday auctions. The overall crowd numbers are higher, the number of regulars tend to be lower because they are selling at the flea market or thrift store, and even the lookie loo crowd is different from the lookie loo crowd during the week. I find weekend auctions interesting because the part-timers tend to way overpay for units, but at the same time , because there are so many novices, the door can go up a unit that being a regular you know is an immediate money maker, and the rest of the crowd will just rebuke it and claim it's all junk, so you can pull a decent unit for less then during the week right under their noses. With Saturday crowds, all it takes for a couple off loud mouths in the back to bad mouth a unit and the rest of the crowd comes into agreement pretty quickly. The same thing can happen with a unit that a few people think looks great, then the part-timers bid the unit out of sight!
As far as attending auctions during the week for people who work during the week you just have to accept you are going to miss quite a few auctions. Look to attend auctions with a high amount of units up for auction. Try to take lunch breaks around the time of auctions so you can attend them, and if you have leave time, take a day or two a month to hit the better caravan runs in your area.
Once you get to know your area, you will find that there are facilities were 80-90% of the time you are not going to miss anything if you can never attend their auctions. Concentrate on finding the time to go to auctions where their tend to be units that are consistent money makers, meaning you always see at least one or two or more units that have the quality of merchandise that will sell.