I train with weights, and I they certainly do not weigh the same on different days. Some days are better than others, a log helps keep me on track.
Of course that's me. It might work for you though. In my coaching experience I find, that most people are not objective enough (or have a good enough memory) to work like that.
Tracking calories on paper vs in your head is a similar objective/subjective mess for most people. The mind is very good at deceiving itself.
I train with weights as well, but I do a whole body routine regularly. It's not very hard to remember the weights (at least the ballpark). I think if you do isolated exercises it'll be harder to remember the weights and a log will certainly help.
Of course that's me. It might work for you though. In my coaching experience I find, that most people are not objective enough (or have a good enough memory) to work like that.
Tracking calories on paper vs in your head is a similar objective/subjective mess for most people. The mind is very good at deceiving itself.