Depends when and by whom. It's interesting to note how much Soviet reports evolved during the war. Valeriy Zamulin has a good breakdown of daily dispatches to recreate a portion of the Battle of Kursk in great detail in "Demolishing the Myth". It's really a day by day, hour by hour breakdown of action over several days that he sources from field dispatches and action reports. There's very detailed data.

Glantz does something very similar in "Kharkov 1942". Glantz also mentions the poor quality of Soviet dispatches at the start of the war, where the reporting officers often tried to minimize losses on paper and shift blame for failure because of a culture of punishment for failure, and notes the improvement in dispatches and after-action analysis as the war went on and the Soviet military improved.

I doubt that the quality of the content is uniform over the continents and years of WW2, but we do have excellent detailed information that has been vetted and distilled by historians about cetain events that can be used to draw a very detailed map. There're also a tons of archival materials that can provide detail.

As an amateur who is currently working on a similar project based upon AARs, I haven't yet located anything that details hourly unit positions consistently for US Army forces. Also, theres significant gaps in documentation for any given unit in the various NARA files that would make it tough to create a fully inclusive map thats 100% accurate on a per-day basis for company-level positions. Division & regiment-level positions would be less-challenging I'd think simply due to the ability to cross-reference positions with fraternal and attached units whose AARs are also available.

This being said, using the unit disposition overlays along with the original GSG maps used does allow someone to accurately display company-level positions in a fairly accurate manner.

EXAMPLE - 143rd Infantry division 5/29/44: http://imgur.com/aowOP2Z

Note that in my experience, these overlays need to be sanity-checked against any coordinates listed in the AARs, which you'd then run through the Nord De Guerre translator to display, then compare to the GSG + overlay results to verify accuracy.

Nord De Guerre Translator: http://www.echodelta.net/mbs/eng-grids.php

Again, I'm just a guy who has been studying this for a year or so, and it's possible (read: likely) that those with more experience in the field can provide some better commentary and advice on this topic.

EDIT: Corrected units listed on map

"In WW2" is a broad and large category.

However, speaking to a specific instance, the German Command (the military side, not the political side) seems to have analyzed the Normandy invasion with accuracy and without ideology. Gen. Von Rundstedt identified four factors that helped the Germans understand what happened in Normandy (note this memo is dated about two weeks after the invasion).

"(1) The enemy's complete mastery in the air.

(2) The skillful and large-scale employment of enemy parachute and airborne troops,

(3) The flexible and well-directed support of the land troops by ships' artillery of strong English naval units ranging from battleship to gunboat.

(4) The rehearsal of the enemy invasion units for their task; most precise knowledge of the coast, of its obstacles and defense establishments, swift building up of superiority in numbers and material on the bridgehead after just a few days."

http://www.history.navy.mil/faqs/faq109-5.htm

Air superiority and naval guns supporting at crucial times were important to the initial success of Overlord. Gen. Von Rundstedt emphasizing air superiority is interesting, because, this is the main reason why Rommel suggested that defense against the expected invasions be focused on the beaches themselves, rather than counterattacking from inward positions. Therefore, this could be seen as intellectual honesty.

In addition, #4 points to, in part, a technology that was developed by the British that the Germans did not know about. Mulberry harbors (artificial harbors) were crucial to getting to getting the Allies supplies ashore much quicker than Germans expected (http://en.wikipedia.org/wiki/Mulberry_harbour)

The Germans knew that supplies would be the crucial limit to the Allies ability to push forward on the Western Front (this is why, for example, Hitler's rather absurd gamble known as the 'Battle of the Bulge' focused on the Belgian port of Antwerp).

One of the master pieces of results analysis was the Butt Report which was a comprehensive and politically impartial which was quite remarkably accepted in its entirety, given the number of sacred cows it slaughtered

https://en.wikipedia.org/wiki/Butt_Report

Basil Embry requested a similar analysis when he took over 2 Group, 2nd TAF and used it to hone the bombing accuracy of the group to the stage where it could hit a specific wall on a specific building, for example on Amiens jail.

A good example of what can be achieved is The Nuremberg Raid by Martin Middlebrook which details with considerable accuracy the fate of each individual bomber that participated, to the extent of sometimes identifying which bomber damaged which building, as well as the actions of many of the nightfighters involved.

On a more personal note, the British engaged scientists in Operational Research. They would objectively evaluate performance and new proceedures and processes, new equipment etc. In the case of my grandfather, this was with AA guns. I have the originals of his work but have never read them.