Most fly anglers I know, with sufficient days on the water, would enjoy helping someone along on any of these outings as much as fishing unmolested. That said, the level of instruction will be much greater at an event designed for such a purpose and usually held at times where most people would be less distracted. The annual Jamboree has many newcomers, and unless they are too shy to ask, I have never witnesses a newcomer be shunned in the social interaction, nor when making plans for the following day.
Go to any of the Board "happenings" and listen and learn and try as may be the case with any gathering. 9 times out of ten, you will get some personal attention that will make it well worth attending and being outgoing.
About everyone I fly fish with have been met through these gatherings.