Mine says that if you get #2 right (you're using a top quality soil that allows you to water properly); #1 is going to be virtually a non-issue; #3, and let me add diseases to the bug issue, will also be much less likely because a plant's natural defenses are a byproduct of its metabolism - good health is a plant's first line of defense against predation and disease; #5 is almost always a contributing or secondary factor to root health. A compromised root system cannot efficiently move water, so in most cases the primary limitation is poor root heath - almost always caused by a poor soil and over-watering; #6, over-watering, is difficult when using a soil that allows you to water w/o concern for compromising root health/function; #7, too much food, is difficult if you use a soil that allows you to flush accumulating salts from the soil each time you water. Even if you're using a fertilizer whose ratio is badly skewed, the flushing is like pushing a reset button every time you water.
I think that 90% of the issues growers for which growers come seeking resolution for are directly related to that little triangle formed by soil choice, watering habits, and the EC/TDS of the soil (how much salt accumulates). Get the soil right and ALL the other issues are unlikely to become a factor - except light and ambient temperatures.
I agree with # 1, my motto has always been less is more, I'd rather have to water them more than have them rot a slow death from over watering. And I've always wondered WHY do they make pots with no drainage holes, makes no sense to me...Good post
If growers have a problem with #1, they need to look to #2 for the answer/resolution. A soil that drains properly and is well-aerated enough to offer your plants even a chance at reaching their genetic potential will be very hard to over-water - even if you work at it. If you CAN over-water a soil, it's a good bet it wasn't a good choice to begin with. You should be able to water to the point where the soil is completely saturated and water is freely flowing from the drain hole - every time you water. If you can't, calling a soil 'good' is probably assigning a value greater than its worth.
Most growers have difficulty growing certain plants because their choices and habits put a large % of the plants they grow at/near the limits of what they are programmed to tolerate. Once they discover there is a replicable sweet spot that allows them to treat almost all plants nearly alike and grow them all well, they're over the hump.