based on past field studies and more recent studies with indoor plants, it's probably better to limit UV use in flower during trichome production.
The reason earlier field crops did not show any benefit from the sun's uv rays was because it was hammered by it from early ages and builds up a resistance to the UV wavelengths... so it doesn't 'stress' them into packing on trichomes later on in life as the indoor studies showed was a response.
IR.. they''ve shown that PAR is not quite all that the plant uses for photosynthesis, so i'm sure it helps from day 1, on the otherhand. Bugbee has shown that a wider range of wavelengths are beneficial, so probably a good chance it's helpful. Check out the related videos for references.
These studies compare clones to a control group of clones where the only difference in environment is the UV application. This is why they are superiour to anecdotal reporting that is just assuming there's an increase based on what they see but never comparing to a set of clones that did not receive the UV... without that it's irrational to assume except in cases in overtly and drastic differences cause which is not he case here.. in the end would have to compare potency with lab equipment for this sort of delineation.