Any monkey can do Freighters! PAX & Combi’s are where the real skills are at!!!
Manual loadsheets are the best, IMHO. If you learn that well enough, you’ll be able to look at a Cargo Manifest & start writing the positions down without bothering with the LIR...initially. The calculator analogy is good. You would have learned to write out sums before you got a calculator...same difference.
Ratty’s advice is true. Look after your downline ports, abuse hell out of the upline ports that screw you, and above all, look after your ramp staff & don’t make them run around like headless chooks! They can ruin your day, big time if inclined to! I never worked on the ramp, so I was very reliant on their skill at estimating how all the pieces would fit. Use their advice & make sure you give credit where its due.
Also...if you are loading some really heavy stuff onto an aircraft, just make sure the destination port can offload it! (PM Ratty for more...)