The notes only say "loads". That should probably mean loads that may vary in length depending on hardware?

There is also one occasion in The Drop that gives you a black screen, when you take the shortcut up the stairs instead of wading through the water and all. Can you count that as a load screen? The skip becomes rather useless otherwise, because if you do that part the intended way, there is no (or a very short) black screen (until "You couldn't set a cloth aflame if it was doused in oil, son"), because the game waits until the guards are in their positions to play that cut scene. In this sense that's not a load screen, but it'd still be sweet to get to include the time "saved" for pulling that trick off, sort of. :)

It's quite hard to figure out what to deduct from RTA not knowing when to start counting the time for a "load screen". A load will start from the moment you clicked "OK" for for example "Would you like to start this chapter?", where the game auto saves and starts preparing the level.

RTA may be the best way to compare run times, but are at the same time totally dependent on what hardware the runner was using (I myself have a monster PC, but I sometimes have long load times either way, with Thief being a poorly/unevenly optimized game).

Personally, I would take "IGT" more seriously if the rules were clear about what to remove from the RTA and it would be more fair to runners that way. For example: "A load screen starts from where you click "OK" in the prompt (your "last input" to go to a chapter or to certain areas) and lasts up until the moment of the first frames of in-game animation. Be they a skippable cutscene (e.g chapters 1, 2, 6, 7 or 8 ) or whatever map is then loaded."

I'm assuming the best and most precise way to calculate all these load screens properly is in an editing software. Doing it manually is quite finicky and rather arduous, but can also lead to quite random guessing.

I have investigated this further and it's clear that "loads" simply means the loading screens with a progress bar. So that's what you deduct. Nothing more. The game's timer runs at all cut scenes. Perhaps everyone already knows this. In this regard, the IGT times are what will matter. RTA differences will not change a run's position on the leaderboards.