Yes and no! You shouldn't worry about it, but you need to practice efficiency to get better at it - and that means maximizing your DPS and finding the correct rhythm for you - you strokes/second or strokes/minute. If you know how many strokes you take in 100 meters, and you know your time for 100 meters, then you can figure all of it out. This is ignoring turns and starts - but if you always do it the same way, you will have the same results. And this will work for freestyle, backstroke, breaststroke, butterfly, even sidestroke.
Stan Swimmer completes the 100 meter freestyle in 1:00, using 54 stroke cycles. What is this "cycles" thing? Instead of counting each arm, just count one arm. A cycle begins when the first arm enters the water, and ends when that arm recovers and enters the water again. That is 1 cycle or two strokes. It is easier to count for most people.
The math and more on page 2....