Water First Rule

[WEA]

I am concerned with the "Water First Rule". Piggy-Back from previous post on "Fertilizing".
Watering 1-2 days before would seem better than doing as I do and water the same day or just before spraying. However, in my orchid house the HAF is adequate to dry at least the plant surfaces out in a matter of hours, and in northern Florida the plants outside (particularly the hanging plants) are dry equally fast. Thus I tend to water just before spraying. "Water First" seemed more appropriate to when I use to fertilize plants in bark infrequently at full strength, than now when I fertilize every watering at 1/4 - 1/2 strength + Dial dish soap.
The only exception to this might be the Phalos that are in sphagnum. If I wait too long to water them, then the sphagnum gets a bit crisp (at least the top couple of inches). Then I might be able to understand watering the plants to get the sphagnum hydrated and more receptive to accepting or exchanging rather than channeling the incoming solution.
The idea that the velamen can only accept just so much liquid rings true, but even then there will be transfer from an area of greater concentration (fertilizer solution) to the area of lesser concentration (water wet velamen) so some fertilizer ions will make it to destination. Will it be enough fore instance to supply that 100-150 ppm nitrogen to the plant that many of us shoot at? Intuitively I think not, but I sure wish someone would chime in on the "Water First Rule" related to 1) fertilizers, 2) systemic insecticides and fungicides, 3) topical insecticides and fungicides. Watering before spraying seems to be a hand-me-down rule from the "old days" of osmunda and bark i.e. organic substrates. How does it apply to modern technology of Perlite, LECA, Epi-Web etc, and fertilizing at every watering with 1/4 to 1/2 strength fertilizer solutions?
I'm already regulating the pH (5.8 - 6.2) of spray solutions for both fertilizers and pesticides based on input about activity levels of active ingredients relative to pH.

While I'm asking questions! One more. I read some place that some vital nutrient components are "best" or "only" taken up by the plant "under the leaves" and at the "new growth tips" of roots. S/H has the velamen and root tip covered, but what about "under the leaves" or on top the leaves for that matter, since I can't remember the quote exactly? I currently add surfactants to fertilizer solutions as stickers based on "old school" foliar fertilizer rules.