This is in no way intended to be an shot at anyone who has ran an event, just constructive criticism to help improve future events. There are many events that have had issues cramming everything into the course of a few days, including ones I've been involved in running. Part of what leaves a lasting impression of a good event is quality field fighting, especially for people that have day tripped. Keeping the field active for as long as possible will make for a better event.
Let me point out a few things that commonly can cause trouble for your schedule.
Getting weapons checked and on the field gets fighting started. The soon you get it open, the sooner people can take the field. Not everyone is going to want to be up early, but you'll find plenty of people up and around that will need gear checked. Post the time at troll and there will be plenty of people stopping by early. Every person you can get through weapons check before 10 am makes way for someone day tripping or sleeping in.
Make sure that the busiest day of your event, usually Saturday, has some of your most experienced checkers assigned to cover it. Pausing to recheck weapons that shouldn't have failed or answer questions from less experienced checkers can slow down the process. If you have less experienced volunteers, try to train them ahead of time (before the event if possible).
We all want to see our friends get knighted. Most squires have a lot of friends by time they are ready to be knighted. That means that a sizeable amount of veteran fighters are going to leave the field to watch/participate. Depending on the size of the event, this has a good chance of killing fighting for everyone else, easily going from a 200+ person event to a large practice.
To minimize the impact of knightings, and other promotions, try to schedule them off of peak fighting times. Saturdays should be avoided, if possible. If it has to be done on Saturday, it is better to either start early or towards dark (if lighting permits). The goal is to ensure that fighting was going to taper off anyway or have time to ramp back up afterwards. Weapons checkers should be able to expedite checking of weapons needed for trials to get them started earlier.
To improve the overall experience, take advantage of the smaller field size during trials to run bridge or castle battles. This will keep the smaller numbers fighting at a higher intensity than a normal practice. Once trials are over, have a plan to lure fighters back to the field, like having realm/unit battles.
Always try to avoid overlapping trials. Work with those involved ahead of time to see how you can space them out. Multiple units having trials and promotions at the same time is multiple units off of the field. If you know several groups are wanting to have their trials at your event, consider renting lights and setting aside time after/during feast.
Ahh, feast, the bane of most event coordinators. There will almost always be someone complaining about it (look, even I'm doing it). It is either too late, under cooked, over cooked, or the line is too long. One thing that is sometimes overlooked is how having feast too early kills fighting. The sort of ideal time is right at dark, leaving as much sunlight for fighting and food prep, without leaving people hungry.
Remember, people that day trip to events van easily spend 6 hours driving the day of the event, they're going to want to get in as much fighting as they can. They will be more likely to make the trip again (maybe even to camp) if they had a great day at your event.