Skipping a day is useful for hypertrophy. Not so sure how useful it is for strength. Pavel Tstatsouline wrote in The Naked Warrior how he makes his clients do pull-ups every time they exit the kitchen or go down the basement, every day, like 5-10 times a day, but the trick is, they don't do it until failure. They just do it as long as it feels kinda comfortable. So basically they need little recovery from that. It is not hypertrophy training, it is more like etching in a neural pathway, although some hypertrophy is supposed to happen along the road.

Hypothesis: I think the major body building or power lifting trainers like Rippetoe, who write the books and make the popular methods, have incredibly lot of willpower. When they train to failure, it means they train so hard that I would run away crying for 20% of the struggle they put up with. This is why they need 48 hours (or more) time to recover or else they get overtrained. But for people with normal amounts of willpower like me, where training to failure means stopping an exercise when it is starting to get uncomfortable or kinda boring or look there is something shiny over there, very little recovery is needed from that. Not 48 hours, maybe not even 12. Remember, people used to use strength all day, every day, like unloading coal. Their recovery was 8 hours of sleeping and another 4 spent on whatever, their "training" was 12 hours long every day. The trick is, they never ever went even 10-20% to what a body building trainer would consider training to failure or muscle exhaustion.

This really should be factored in! People who are unable to go anywhere near the intensity of the pros, people whose weight training feels a lot like unloading coal (it gets tiresome or boring and thus stopped earlier than it gets real muscle failure), don't need 48 hours of recovery and basically will never be overtrained.

The problem is, this is something the pros don't write about this problem as it does not exist for them. They tell you to use 60% or 70% of your one rep max, but what does a one rep max even mean? Does it mean "I either lift this or die here" level of dedication, or does it mean a "well, a weight bigger than this would feel kinda hard and I am already sweating and feel a bit tired and I need to meet Joey for a beer in 25 mins, so let's call it 1RPM and call it a day", which is more likely for mere mortals?

That is why listeing to pros is suboptimal for mere mortals.