How much time passed on Draenor from the time the first orcs made it to azeroth until they summoned the rest of the orcs to azeroth?
Or is blizzard ignoring the fact that time on other planets or planes of reality passes differently than other planets and reality
So, three parts to what I’d say the answer to this is, and a long definitional statement as to how I got there.
So, the nature of the Great Dark Beyond/Twisting Nether is ambiguous. The problem is that Warcraft ‘Physics’ conflates a Time Dimensional Axis (overlapping planes of existence/reality) with the concept of Physical Space (as opposed to Time). The Twisting Nether/Dark Beyond exist as terms for the distance and nothingness between worlds, which means both what we define as the vacuum of space outside of Astral Bodies, as well as locational nomenclature for the ‘alternate dimension’ of Destruction. If we take the ordering of the Universe as gospel and that Time is a function of Order - then one may presume that the Twisting Nether, as a function of Destruction and as a pure opposite to Order, does not operate with a naturally equivalent concept of Time.
What does a universe without time look like? Using simpler concepts of something occurring Eternally, that can mean that a single moment occurs all at once in an expansive or retractive way. Eternity either expands to encompass everything in an all inclusive moment (Everything is always occurring) or Eternity collapses so that everything retracts to a single moment (Everything occurs all at once). We do not have an actual human comprehension of a second spread to infinity, but we can potentially conceive of having infinity compressed into a second. Also, the concept of having Eternity conceived as a collapse into a single moment would also be more in line with a concept of destruction.
So, given a concept of the Twisting Nether having a time compression effect (perceptually), I would say that using the Twisting Nether for transit is appropriate, as regardless of time variables on either side of the portal, it is effectively instantaneous as everything in-between happens instantaneously.
Also, the Draenor we are aware of is part of our ‘universe’ or Material Plane as a planet, as is Argus and the other Astral Bodies. Despite it having a different rotational cycle, a second is still a second when measured, a person going to Draenor for 10 Azerothian years only ages 10 years (temporally, not concerning ourselves with physics and chemical differences of an alternate planet) by our standards, despite the other planet having a difference in what a year may consist of.
Additionally, we know that Order and its function of Time is infectious, through the revelations in Shadowlands. Time is to the Titans as the Curse of Flesh is to the Void, a manufactured and infectious byproduct of their presence. Just as the Twisting Nether can be used to breach the space between spaces in the material plane, it also introduces measured time into the Twisting Nether.
So, hypothesizing that
We can postulate that those travelling into the Twisting Nether can perceivably travel ‘safely’ by virtue of having a protective bleed of standardized Time around them.
Now, that creates a second issue. If the Twisting Nether exists separately as a compression of time, how does one find the ultimate destination for the portal? This would be conceivably why Gul’dan required Medivh to help connect the portal initially, because otherwise the Portal could drop somebody off anywhere, any time in the universe. The two created a bridge between moments and stabilized the portal so that the two places and moments were linked, so that stepping through one side, brought you through to the same moment on the other. This would also be why the Portal could then be used to create a portal to the alternate Draenor, as a connection to the same place - but an alternate moment.
This would also be why the Demons have easy access to alternate timelines, because the Twisting Nether is all moments compressed into one, allowing them to step out and into the Ordered Universe at any point, but also why they need Demon Seeds, Beacons, and Ships, to help them navigate to the appropriate time and location in the Ordered universe.
So to directly answer your question, I would contend that"
For the purposes of the Dark Portal, time is standardized between the two worlds so that the only difference in time from one side of the portal to the other is a matter of the time it takes to move through physical space through the threshold.
Time does not operate differently within the boundaries of the Ordered Universe. The tick of a clock is the same anywhere the Titans touch (as a perceived unit of Time).
Differences of the passage of time is a matter of relativity and perception. Bridging the worlds with the Dark Portal removed the uncertainty and distance of relative perception of time.
Thus, the time between is whatever time the narrative indicated they perceived.
Edit and TLDR: My hypothesis is that if you took four stopwatches, two on each side of the Dark Portal, started them at the exact same millisecond, and had one from each side sent to the other, all four stopwatches would always read the same time has elapsed, no matter how many times or in what order they are sent.
What are you talking about, time on other planets passes the same as it does anywhere else, the only thing that changes is the increments or method of measurement, the actual quantity of time itself is the same.
Planes of reality, though, those could definitely be different yeah.