The problems i've encountered when trying different methods of measuring cam lift is that:
1) If you try to measure on the cam follower, it has no return spring, so it travels up the tunnel to full lift, and stays there. You need one hand to turn the crank and one hand with a screwdriver pushing the follower back, acting as a human return spring.
2)If you measure at the cam lobe it's a long way inside the engine and it's hard to get the dial gauge set on it properly.
3)If you measure at the top of the pushrod, the pushrod is loose in the tunnel and flaps around and it's hard to get an accurate reading. You also have the return spring ( lack of) issue.
You simply need to find a method that works for you and ensure it gives repeatable results.
Securing the dial gauge is often the hardest part. Mine has a magnetic foot that is pretty well useless on an alloy engine :)
The trouble with the world is that the stupid are cocksure and the intelligent are full of doubt.