A lot of people would describe their minds as cluttered and disorganized.

If you were given the task of finding a specific item in a messy room, then it would take a long time and would probably be frustrating. If this happened once, then nothing would really change. If you had to continue finding items in that room on a regular basis, though, then eventually you would just clean the room so that things could be found more easily.

I believe the same thing can happen with our memories. If we spend time and effort trying to remember things, then behind the scenes our mind will start to organize itself better so that it will take less time and effort the more often we do it.