I saw this press release from CRMXchange today. They point out that they are seeing a marked increase in companies putting on an integrated series of webinars, rather than single one-time events. I agree with their perception. Many of my clients organize training, education, or marketing topics around a group of webinars instead of a single webcast. Putting together a series has a number of advantages. If a participant can't make one of the events, s/he can try for another one. You can grow familiarity and trust with your audience over time, rather than having to do a hard sell in a single shot. You can dedicate time to serious coverage of a topic, rather than hitting high-level bullet points about a lot of things at once. And you get an indication of people with high interest level in your subject simply by looking at how many events they signed up for and attended. You can also usually simplify and speed the registration process by allowing people to sign up for several events at once.
Some companies schedule a regular weekly day and time for their webinars and adhere to it for consistency. I prefer to shake things up and try different days and times. You may have picked the same time as someone's weekly staff meeting, or their regular lunch hour, or their time for rounds. Who knows? Give yourself the opportunity to catch them at another time more convenient for their schedule. If you have the potential for international attendees, make sure to consider their time zones and see if you can throw in something more comfortable for other locales. I see that CRMXchange puts a link on their webinar listing page to my favorite online time calculation utility: TimeAndDate.com. This site is indispensable for figuring out local times anywhere in the world. If you go to their Fixed Time World Clock page, you can enter the date and time of your event and produce a quick reference guide with local times for attendees anywhere in the world. People appreciate not having to do the conversion themselves.