I hear you, and that is something I consider. A big part of why I don't do lunch seminars, people are still working, and get at most, an hour break.Caveat, NOT an agent. (and I have never conducted any type of seminars.)
While I was still working, a 5 pm start time for something would have been a big problem. And it seems to me like even a 5:30 start time could be a problem in a large metropolitan area for those still working.
It seems to me like 6 would be better, but that is just a comment from a former 8-5 employee with no experience in conducting seminars for a group of potential attendees who might, or might not, still be working.
But, the locations I do my seminars at close, at the latest, 7pm. So a start time of 6pm wouldn't work. 20-30 minutes for presentation, 20-30 for Q&A and rapport building, doesn't leave much of a buffer for tear down and leave by closing.
I have experimented with Saturday seminars as well, not much of a difference in attendance to my evening weekday seminars.