While I stuck to meter readings in the beginning, it became obvious over time that they did not tell the full story with conditioned batteries. If I am charging for one hour at 1 amp in and get a return of 2 amp hour out over the same period without a loss in the battery, that is all that matters to me. Usable power beats meter readings for me every time.
Yes, I start to believe that meter show amp too small compared to the real consumption. Either for output and input. But I use output vs input ampere to see the efficiency of a device. Or how long a circuit charge a battery with same number of consumption.