It's said that "An animator is an actor with a pencil". The point remains true even though you are using Blender instead of a pencil. A good animator is also a good actor. This is true even for something as simple as rowing the boat.
Think about rowing the boat. Basically, you dip the oars into the water, move the blades backwards with respect to the boat until the stroke is done, then lift up the oars and move the oars back to the starting position. So how long is that motion going to take?
All animators should own a stopwatch. You can get an inexpensive one on Amazon or at a local store. If you don't have one, you can use a clock or this online stopwatch http://www.online-stopwatch.com/large-stopwatch/. But neither is as convenient or as accurate as a stopwatch.