Arnold did his thing; however, no one should follow in his footsteps because that's once again HIS thing. In no way should your average Jo or beginner train like Arnold, when you're on different levels, you should train like that. A beginner training like Mr. Olympia is an epic fail.
Mr. Universe should train like Mr. Universe, not to mention, after hearing some of the things Arnold said I've found him to be a complete moron (I'm entitled to my opinion!) Once I heard him say "arnold presses overload the posterior and anterior deltoids. That's not true, if you need me to elaborate on why, feel free to ask.
Fly's after bench presses are fine, if you feel you still have the energy, especially if you like the feel of pumping blood into the muscle tissue. Doing only one exercise can will work, especially with beginners. With beginners, less is more (once again, not calling anyone a beginner).
The smith machine isn't as effective as regular free weights, that's the moral. You say the smith machine works, well you can cut your lawn with scissors and say it works, but so does a lawn mower "to each is own" is up to you, but which does the better job?
The three pros of conventional free weights on a smith machine
More Strength & Muscles. Squatting with free weights is harder than inside the smith machine. You must control & balance the bar. Exercises that stress your body more give better results.
Functional. Pick a heavy object from the floor, put it on your back & get up. No machine balances the object for you. You must do it yourself. This is functional strength. Smith machines don’t build it.
Safer. You decide where the barbell goes when using free weights. The smith machine forces you into fixed & unnatural movement patterns. This can cause injury.
Source:-
http://stronglifts.com/why-you-should-always-squat-with-free-weights/
The person performing the range of motion should balance the weight himself using his stabilizers, how exactly does a weak stabilizer benefit someone looking for function strength / overall development? Not at all, training on a smith machine then using free weights (unless, of course you have an injury) is complete backwards training.
A bench press can and will pre-exhaust the triceps, anterior deltoids, lats, traps, core, and can give the glutes (if you're lifting heavy) an optimal workout. They overload and utilize different muscle groups which is why they're essentially the bread and butter of a mass building exercises, if you feel you'd like to work the chest more with fly's, crossovers, and I love incline bench presses, then sure, after you do the compound and get the optimal/more dominant exercise in, feel free to isolate the muscle.