Precise control of an airplane’s power is not that big a deal, that is, unless you want to fly precisely. In that case, it’s an absolutely critical part of the equation. Unless you control your ship’s power very accurately, you can’t nail the numbers, and nailing the numbers is the key to nailing the performance. And that matters a lot on everything from check rides to short field arrivals. If you’re 15 knots fast on base going into a short field, you’re in trouble already.
Unfortunately, it can be hard to accurately control the power in many airplanes simply because of the way the throttle control is implemented in the cockpit. Ask for a little throttle in many, and you get a lot of throttle instead. Ask for even less and you often wind up getting none at all. Part of it is in the design of many throttle systems (lever, linkage and cabling), as there’s simply too much slop built into the controls. Part of it is in the whole need for mechanical advantage. Put a long lever on anything and you get great power and limited control.
The keys to taking control of power adjustments are two things, friction control and hand placement.
Most airplanes have a control to ratchet the friction up or down, so it’s harder or easier to move the throttle. If you want to get fine control, then you need to make it harder to move, not so hard that you can’t get a quick dose of power when you need, but hard enough that you don’t accidentally get a lot more than you asked for. I like it adjusted so it feels hard to move but just barely not too hard.
The other key is hand placement. Lots of pro pilots don’t grab the knob at the top of the lever but the lever itself, so they’re effectively choking up on it. If you move your hand way down toward the base, you’ll find you get little power and fine control, which is just what you want in some cases.
With push in throttle types, as on many Cessnas, you can do the same kind of trick by bracing your hand on the panel to the left of the throttle control in a way that braces your hand against moving too easily. When done right, you’re pushing against the pressure of your hand holding itself back from pushing. This allows you, again, to get that fine control you’re looking for.
When you have it, you have it in your power to fly with the kind of precision needed to make good (or close to it) on the performance numbers you see in the POH.