I wonder, if we might compile a list of the quests, that are on timers, i.e. where the outcome depends on how long it takes you to get round to finishing them. I certainly would find such a list useful, and I think there may be others. Especially as it seems not always clear which ones are timed.
For example I’m at “If you can’t beat 'em”, and have no idea if I can take a break from mainquesting for a while to indulge in hunting and leisure…
It sounds like a brilliant idea!
Okay, the first main quest on a timer, I think, is when you have to investigate Neohof. Bernard will ride off without you and be quite upset with you if you don’t go with them. I just have to put my game from hunting with Capon in my horse to save on weight.
As for side quests on a timer around the same time…no clue.
If you are helping Johanka treat the injured at Sasau, that is on a timer. If you can’t read or do Alchemy, or have bandaging skills from the main level tree, it will be very difficult to save everyone.
Okay, let’s try and find the precise names of thew quests. Then I’ll update/edit the original post to list them …not sure if alphabetic order for side quests and order of occurence for main wuests?
Now this is what I call a good and useful thread, unlike hundreds of other useless threads. 
Finding Reeky, main Quest wait to long and runts men Will have found him and leave him in his cave All bloody and close to death (you can not save him then) between a rock and a hard place, once you start you have 5 days. A cure for merhojed side Quest. Dont know how long when you start it dont delay to long considering once you give the anti dote it Will take 2 days for the game to tell you of everyone died of lived
I’d assume the best use of this list would be to limit spoilers to a minimum, I.e. not giving away the days r times frames required or consequences etc. Just listing the quest by the official name and that it’s timed.
I’ll see tomorrow or so, if I can scrape a few points and quest names together.
Do you recall the name of that mission?
I use this list posted on Reddit :
WHY : out of respect for myself and my time, as it is not obvious which are timed and which are not.
Here is a real example: I am told to urgently go to Talmberg to prepare the battle against the bandit/Cumins near-by, but that main quest is not really times 
But I accepted to negotiate for the Talmberg’s Quarry and that side-quest is timed! So the economic issue, which logically is really less important than the impeding attack against Talmberg, is timed, but not the main quest (careful: or so I am told: the step I mention here, after informing Sir Radzig about the bandit/Cumin camp, maybe has a time limit or consequences for delaying!).
I have fully played the game and, after watching many videos, came back here to suggest it would be an important improvement to add a clear marker on timed quests (can take many forms and could include a time estimate).
I am of course not the first to suggest this, but I want to add my two Groschens in favor of this. It is crucial really, as first-time players might build something in Pribyslavitz (From The Ashes DLC), causing time to pass suddenly and fails. Some quests do seem timed while others who really are might go unnoticed.
It does not make the game easier or less hardcore : just avoids the player wasting many hours in some cases.
At worst, maybe a modder could add a special marker/indicator for timed quests (a simple mod: nothing fancy). Otherwise, players can use the known list (link above), as I did.
I have yet to encounter any timed quests, except House Of God, and even there I was pretty fast about finishing the quest in a relatively fast manner. I tend to finish quests pretty quick, so maybe I’m just not noticing that a few are time-sensitive.
