The SCAP Hardcover open to 2 sections, one page to get the Umber Hulk's stats, and another to see it's tactics.
The MM open in 2 sections, one page to the Umber Hulk page to get the full description of it's Confusion ability, the other page to the fiendish description to make sure that the template didn't affect the Confusion save DC.
The PHB open to the Confusion spell description.
The DMG open to the page with rules about dealing with crowds.
The Rules Compendium open to the rules about dealing with gaze attacks.
This was just a bit of an extreme case.
That was very much an extreme case. When I ran that encounter (from the magazines, not the hardcover, so it might be different), I didn't need to access the MM, since everything I needed for the monster was in the magazine. The magazine also gave the info I required for dealing with the crowd, and I happened to know the rules for gaze attacks. So, I made do with two sources, the magazine and the PHB.
However, the larger point is a good one - this game has a lot of rules spread out across a lot of sources. And in 3e, it's not arranged as well as it could be, especially when dealing with monsters and spell-like powers. The 4e designers were probably right that creatures should have fewer powers overall, focussing on their 'signature' powers. They are certainly right that everything you need for a monster should be present in the monster description.
Additionally, the 4e 'exception-based' design is somewhat easier on the rules look-ups, since you only need to know what you need to know for the encounter; everything doesn't connect to everything else as in 3e.
(However, there are also big downsides with exception-based design. Firstly, it runs the risk of exceptions being forgotten or overlooked. Secondly, much more effort is required to make sure all the exceptions are placed where they should be - in 4e you can avoid the Medusa's gaze by closing your eyes, but not the Basilisk's gaze. Thirdly, there's a danger of 'duelling exceptions' where one special case contradicts another, and it's not clear which should have precedent.)