The Importance of Condition and Fitness

First off, I'm sorry if this is already covered in other threads, but I simply couldn't find it.

My general question is - how and when does the Condition value work? Since the early days of CM3 I've stuck to a thumb rule of never playing players below 90% in condition and usually looking to substitute as they approach 70% - and that has worked quite fine. But as I generally play with heavy pressing and loads of running I find the condition and freshness of my players is completely central factors.

I know many of the general assumptions about these mechanisms and I naturally assume common knowledge such as that players without match fitness will tire more easily, that tired players will make mistakes and run less etc. But I am interested into understanding precisely how and when tiredness and condition affect the play.

My practical questions are:

1) How does condition actually work? Do 80% condition players make 20% more mistakes or do they run 20% less? And is this influenced by determination and body language as I would assume?

2) How does the amount of kilometers run affect condition? Is it linear and is it affected by other attributes than Stamina? Does Work Rate determine how far the player does run or how far he CAN run without tiring?

3) How do tackles affect condition? I have observed that a "knock" can sap 20-30% condition that is then regained. How does this work and do tackles in general sap condition?

4) Do other match events affect condition? Or other attributes?

5) How does the re-generation of condition work? How much is gained from resting days, match prep training, regular training, travelling etc.? How precisely do mental attributes and club facilites influence this?

Again, I do know how these mechanisms work in general terms. I'm interested in concrete knowledge about the precise game mechanics and the strategies of other senior players into this crucial aspect of the modern game. Thanks in advance

1) How does condition actually work? I would imagine it’s like in real life. Players don’t technically run less, they run slower. Since they are covering space slower, they’re essentially arriving ‘late to the party’, they stop their run as the attack has finished.

2) How does the amount of kilometers run affect condition? Is it linear and is it affected by other attributes than Stamina? Does Work Rate determine how far the player does run or how far he CAN run without tiring? As far as I’m aware, work rate is linked to a player’s ability to follow your match instructions. I don’t think it determines how hard they work or effort they put in as this is probably covered by their determination and professionalism stat.

3) How do tackles affect condition? I haven’t noticed tackles causing a decrease in condition apart from knocks. These are essentially what a lot of people call impact injuries; they can be ‘walked off’ as they generally hurt for about 5 minutes.

4) Do other match events affect condition? None that I’m aware of. I would imagine that weather and pitch conditions could affect this but I’m sure whether this actually happens.

5) How does the re-generation of condition work? I have no idea what the benefits to rest days are. I always rest players after a match because it’s logical. Travelling and match prep has no effect on condition. I’m pretty sure training has limited or no effect to condition.

Mental attributes and club facilities have no effect on condition.

Half of what I have said could be complete rubbish but it makes logical sense to me. FM is pretty logical and agrees (mostly) with how I think, I’m usually right more often than I’m wrong.

You want concrete knowledge but what your asking for is quite a minor and simple part of the game. Most people won't have anaylsed it in the level of detail that you want.

When in doubt, use your common sense. Since common sense is rare, probably do the opposite of what you think you should do. If that doesn't work, play as PSG