I agree ... I think they did use the whole tube.
************* Scene from computer building shop ************************************
... Opens thermal paste tube ...
Looks at end of thermal paste tube, then to CPU, then back at end of thermal paste tube ...
Aims in general direction of CPU ... Hee Hee Hee ... Spurt
... Jams on heat sink and closes side of computer.
Seriously, If you paid that person to build the computer, I'd be wanting a refund.