If the event is simply being recorded for later post, then the amount of work is determined by what is being captured. If it is just what is happening onstage, then the usual camera/cameramen considerations come into play. Do you want a Jib, do you want to capture incidental action such as backstage interviews, etc?
The lighting is always a consideration. The smaller the venue, the more important to arrange for your own light. If a video truck or pre-wired production vehicle is employed, it usually saves a lot of the prep time as most of the equipment is already set up inside the truck. Now you just have to deal with parking, power, and cable runs. If the event is straight-ahead, then a competent crew with reliable equipment will be a straight-forward process.
If a Fly-Pack arrangement is used, then you must allow for considerably more time to ensure that all of the equipment is properly connected and functioning. The outgoing broadcast/stream is also a variable. Is there fast/reliable broadband at the site? Are you using wireless? Is it microwave? Satellite uplink?
If the event is being broadcast/streamed live, then a host of other considerations move to the top of the list. A host, a script, communications, lighting, makeup, teleprompter, theme music, graphics, video clips, interviews, lower-thirds, spots/advertising, live text, power, cable runs, generator, rehearsal time, crew hours, advance lighting crew, and more must become engaged.
The majority of the time is spent in advance creating the live event and ensuring that you have every second of the live broadcast mapped out. The YouTube mentality today has brought the production standards crashing to the floor with most productions being just horrible events that look like little more than a security camera online. There is no sense of time, no urgency, no desire to start an event on-time or end it on-time. Kids producing events today just seem to connect their stream whenever it happens, and if it goes in and out – who cares? No graphics? No host? No signal? No problem!
We strive to produce the best-possible quality live events within a reasonable budget. It simply takes an enormous amount of time to prepare for a professional-looking event. Take a look at any network awards show or Monday Night Football for a top-shelf production. This is your standard. The very least you can do is to follow the format and prepare for as many contingencies as you possibly can. This can only be guided by experience.