You need a lot less drag than the weight of the target fish you seek. Line capacity may be the limiting factor if you're trolling in deeper lakes, using outriggers or running way back of the boat. Even the 5500 is going to have more than enough drag to handle 10lb rainbows in open water.
The past fifteen years have seen reel manufacturers get into a willy-measuring competition over how much drag they can build into a standard low profile baitcaster typically used for bass, salmon and steelhead. My old Chronarch 100s could apply 6lbs of drag if the star drag was tightened as far as it would go. That was fine for steelhead to 20lbs+ (at least if they weren't leaving the pool: 170 yards of capacity with 14lb Fireline meant you needed track shoes some of the time). There are special situations when a small line capacity reel needs a big drag. Fishing in the mangroves for snook or barramundi is one: if they get four feet of line on you, it's goodbye.
As it so happens, about seven years ago I bought an Abu Revo baitcaster for its 10-bearings and longer casting capability. It did outcast my Chronarchs and Chronarch SFs. It also came with a claimed 10lb drag. I was curious how it would perform on a big fish. I've had a few chances over the years to put the Revo to the acid test and it's been far worse than the Shimanos I otherwise use. The Revo DOES have a tighter drag when it's cranked down, but at normal fishing levels the drag inertia is too high. I lost fish because the reel wouldn't release line fast enough. Then I started fishing a too-light a drag because of that inertia, but I missed fish by not getting good hook sets. It's now my least-favorite reel especially with Shimano's more recent E6 and E7 Chronarchs casting just as far and having better drags.
In summary, unless you're throwing poppers around coral heads for GTs in the Seychelles, I wouldn't buy a reel based on maximum drag settings. It's a red herring.