Chu,

I think the noon time thing is for water conservation in drought areas and water is expensive or rationed. It also depends on the types of plants you are growing. Some plants need humidity and some die from it. Trial and error is the best and faster teacher for your conditions. Be wary of one rule fits all in irrigation and gardening. JMHO Aloha

You are correct young plants need water more often. I just installed a nursery clock where a certain row of plants gets a short burst every 10 minutes or so. Only certain plants are on this table.

Plants are each individually different some plants cannot tolerate watering daily such as cactus. Other plants can handle it three times a day such as Bermuda.

Keep in mind rules of thumb, like the noon time watering, are generally safety rules to tell the masses of people who don't want to do much study, but they want to have plants.