I have been looking at the Russian and Bulgarian Olympic training methods and have had unbelievable results. If you care to research the Bulgarian method you'll find that there is a huge amount of volume training twice a day every day on the two lifts, snatch and the clean and jerk, and front squatting. This is too much for the average lifter. The principal of high frequency and high volume is there, but it is impossible for the body to recover, and it would be naive to think that no steroids were used a decade or so a go, before it was illegal.
The principal I have taken to is high frequency and and high volume. I train everyday, starting with squats (Ass-to-grass). Squatting to MAX everyday has increased my 1 REP MAX by 30Kg in 3 weeks!!!! There is the underlying principal is that there is no such thing as over-training only under-training. To an extent this is true and my body has conditioned itself to the lift. Between sessions you will need enough time to eat and sleep in order to recover and maximise gains, which is why training more than this day is not advised.
Along with back and front squats, I add in Bench press, shoulder/push presses and of course the snatch, cleans separately from jerks. Also I add in pause squats on some days.
I used to think you should know what you are going to do in the gym, what weights, sets and reps. But this never accounts for how you feel on a particular day. Keep your muscles guessing, decide on weights sets and reps on how strong you feel.
I always train even after a heavy night out, hungover, aching, in pain, feeling sick, having a cold or illness. Always train. You'll be surprised at what the body is capable of. On days where I've felt so ill I've hit personal records.