One thing people don't usually think of is to be sure to clean UNDER the gasket, if sand and salt etc build up under the gasket that goes around the cleanout plug it can wedge the plug tight when trying to remove it especially if you don't remove and rinse the plugs after every use.
If you do get a stuck plug try filling the tube above it with ice, let it sit an hour or longer then tap down solidly on the T handle with a rubber mallet or block of wood to loosen it before releasing it, if it is still stuck repeat the downward force on the T handle and then release it and pull up again possibly you may need a rope tied to a 2 by 4 and use it as a lever to put more force on the plug to release it from the hole.
The internal workings of the clean out plugs have a very small spring operating the internal tray that locks the dogs in place, leaving the T handle up when not in use compresses that small spring and that may weaken it over time . It also holds the tray back and can allow for deposits to build up in the track that the tray slides in. This can prevent the tray from locking all the way forward and lead to a plug failure.
ALL clean out plugs from the year 2000 to today have the same internal workings , although you may rebuild your bottom part of the plug with a newer and supposedly slightly smaller bottom half that is supposed to reduce the issues with the plug getting stuck in the tube when you need to remove it, the top half and the internal parts have not been changed and may blow out with no warning.
See this video for a better understanding of how this can occur.
. Cleanout plug failures can vary from a slight blow out where the plug sits sideways in the tube ,allowing water to flow past it that can fill the engine compartment up to water ingestion in the engine if you don't catch it in time, "this may actually be the worst type" if it leads to water ingestion in your engines. Usually you notice the boat is not performing properly and you stop to investigate the problem before the engines shut down from water ingestion.
You may also experience a violent blowout that actually launches the plug from the tube, shuts your boat engines down and usually damages the rear hatch as it blows it open. All depending on how fast you are traveling when the plug releases , understand that the bottom of the plug is actually the bottom of your boat, right inside the intake tunnel in front of the pumps so you can imagine the amount of force being applied to that surface at speed and worse yet in rough conditions. The bottom of the boat takes a beating.
Maintenance of the cleanout plugs is always a good idea. Just remember with a boat the better you take care of it the better it takes care of you.
