|Hi, don't leave any troops in your castle, that is useless.|
You will have more troops every time your combat level goes up (for new troops or upgrades you will have to build new buildings).
For a dark elf, you should have the same number of troops; however, some choose a different distribution in the recruiting window; just play around with the switches.
e.g. a level 3 dark elf will sometimes have 13 rogues and 10 minos, or 10 rogues and 13 minos, or 11-12,...
For demons/knights there can be a difference: a knight combat level 3,level 2 can have more troops than a knight combat level 3, level 1.