Different editions of Dungeons & Dragons have different philosophies on how to structure adventures. Earlier editions worked with resources that regenerated very slowly, usually once per day, like spells. And hit points also regenerated slowly. That enabled a style of adventure where these resources were depleted by many small fights, basically what a MMORPG player would call trash mobs. 4th edition has less of those daily resources (daily powers & healing surges), and more resources that regenerate between fights after just 5 minutes of rest. That means that trash mobs are less viable, because players can beat them without using daily powers, and will only spend a minimum of healing surges between trash fights. So 4th edition fights tend to be more epic, which has both advantages and disadvantages.

One frequently cited disadvantage is that a single encounter can take an hour or more. But in practice it turns out that encounter duration is less a problem of the combat system, but more a problem of how well the encounters are run. You can shave off half of the time needed to run an encounter by simply preparing it well as a DM.

For my current campaign adventure I prepared battle maps for all adventures. The monsters are tokens, some of which came with the adventure, others with the monster vault. I keep track of initiative with little initiative "riders" placed on top of my DM screen. And I have a page prepared for each encounter on which I keep track of hit points and status effects. That works quite well once set up. But as I had one folder with all the maps, one box with all the tokens, one box with all the ini riders, and one folder with all the score keeping pages, the current adventure revealed a problem: With 33+ encounters in the adventure, it still takes a lot of time to get everything set up. Especially at the start of the adventure, where I had no idea where my players would be heading to, as the sandbox nature of the adventure gave them a lot of options.

But in the previous session my players descended into a dungeon. And we even stopped at the start of an encounter, just before rolling initiative. That means I have a much better idea of what will happen next. The players will most likely play through that encounter next, and after that they are likely to want to explore the dungeon further. So now I already sorted my prepared material in advance. The map, tokens, ini riders, score page, and any handouts I might want to show for one encounter are now in one transparent envelope. I haven't done those envelopes for every single encounter in the adventure yet, but I'm covered for those most likely to happen next. I'll do the others later.

Preparation takes time, and that isn't every DM's cup of tea. But we only play once or twice per month, which gives me a lot of weekends to prepare each session. And the time I spend preparing then results in less time spent during the session with boring administrative stuff, and more time spent actually playing and having fun. Even if I must say that Madness at Gardmore Abbey due to its size and structure takes more preparation time than other adventures, I still feel the time spent is well worth it.