Guild Wars 2

I have already searched gw2wiki and other sites but i haven’t found the answer yet.
Your experience gained each run is being reduced every time you join the dungeon.Let’s say you get 100 exp the first run,50 second,35 third and so.When will i get 100 exp again?

Sorry if there’s something wrong with my English its not my mother-lang

The true answer is unknown. What you are experiencing is diminishing returns (or DR). This is an anti-farm code punishing players for extensivly doing the same thing over and over.

For dungeon tokens (wich is often called DR but is actually a different mechanic) there is a very strict pattern. This pattern is per character and is reset when the daily rest is done (1h15 minutes from when I post this). For things like experience reward it is more difficult, it mostly character bound, but also account bound, so doing things on other characters helps, doing other things on the same character helps more.

The true mechanic after this is however unknown. This is an anti farming mechanic. on one hand designed to promote people to play different aspects off the game, but also to stop bots and users of third party programs to have an unfair advantage and do illegal things. For the last reason the exact mechanism in unknown and no communicated. if it was an answer as easy as you are asking, a bot programmer would have it very easy to program his bot to go around it.