fact is that even renderers like MAX or even Prman via alfred that do display the progress dont know how long its going to take it might take anything from 40 times that time or 1% of it (ive seem both, so i prettymuch skip the predictions entirely). One can calculate it if one wished... but as said ist a GUESS.
se NOBODY does knows how long it takes untill its been rendered, they can only know how long it would take at the current speed, wich isnt the same. ots totaly possible taht the last pixel uses as much time as all the other pixels combined (altough unlikely)
The best you can do is render the frame thats most busy and take its time and multiply by number of frames. And yes a computer cant do that for you because your faar more intelligent than it is.
