Some programs "fluctuate" session to session, over the course of the week. Like Rip is talking about. 5/3/1 "fluctuates" session to session, but over the course of 4 weeks.
So don't worry, the flux is in there. Every good program is good because some smart dude included all the important stuff into it. Most good programs use the same principles, or ideas, just arranged in a different way. Run the program as it is written, and "try out" the way it is arranged. After a month or 2, you'll understand why it's like that.
Then, if you want you can run Rip's program, and get a feel for how it works. And why its set up like it is.
After that, you'll understand that the 3 programs are not as different as you first thought.
-I could tell you that you don't always need to do a hit a lift twice a week.
-I could tell you that pressing will compliment your benching.
-Or just say that you can do your assistance(dips, rows, back raises) moves heavy one day(4 sets of 6), then lighter(3 sets of 12) the second day.
But you really have to just try it out, and learn for yourself. The sooner you try out a few different things, the sooner you'll know what's best for you.