Knobby,
In a popular vintage aircraft, when flown solo, it is impossible to change the altimeter in flight - It's in the front - you are in the back. So it's a case of adding or taking 30ft's as you go and the old rules of thumb are very relevant in order cross check yourself. It's surprising how easy it is, especially when the workload is high, to get it all the wrong way around.
What I'm trying to say is, what is irrelevant to you as a PPL may be very relevant for someone else.
Kingy