CS-25 / FAR 25.107 defines V1 as the maximum speed at which a rejected takeoff can be initiated. But the real pilot's understanding: On a wet or contaminated runway , the stop distance increases, so V1 must reduce — but only if the operator has stopway or clearway credit. If not, V1 is often limited by VMCG (minimum control on ground).
Beyond the raw knowledge, your collection of ATPL notes serves a psychological purpose. When you sit down at the CAA or FAA testing center, the feeling of "I have reviewed my entire binder three times" provides a calmness that raw cramming cannot produce. atpl notes
If ATC gives you QNH 1020 and you forget to set it (leaving 1013), your altimeter reads 1013/1020 = lower or higher? CS-25 / FAR 25