A well-run mock exam should feel a little boring. You know the format, you know the pace, you make some mistakes and catch some. Your score is within a predictable band.
If every mock produces a huge emotional swing, something is off. Either the mocks are wildly different in difficulty, or you are treating each one as a referendum on your entire future.
The individual score does not matter. The trend across five mocks matters. Track it. If it is flat, look at what you are doing between mocks and change one thing.
One useful trick: after each mock, write down the one specific thing you will do differently on the next one. Just one. Fixing everything at once fixes nothing.