Phase 1: Learning to think, see, hear and speak. 

During the initial years, testers are all ears. Anything is new and hence they learn a lot of things without knowing the learning is happening at great speeds. They are learning to think, see, hear and speak. A bug they miss and or a bug they find teaches them a lot. A success or failure amounts in equal learning. The joyous period of a tester is this.

Phase 2: Structured ideas, structured observation, structured listening and structured communication

StructureYes, that was intentional. So what happens to those joyous tester over time? Too many ideas and any testing feels incomplete. They become dissatisfied with their own testing or feel complacent to grow over confident. Unless,  structure sets in.

The good ones seek structure. The bad ones continue rejoicing chaos and create more confusion as they learn. Structure is meta to fit in ideas without disturbing others.  Structure is racist. It treats the good and bad differently. To good, it helps bring peaceful testing. To bad, it leaves them dissatisfied.  An expert is someone who has enough ideas, structured. Anybody else is wasting your time.