The current cap is 50 coins per day for holding a gym(s).  This causes said pokemon to of course be unusable while in the Gym.  What happens when you hold a Gym(s) for multiple days?? You still get the same 50 Coin daily payout.  I feel this is a cheap tactic, and cheating good wholesome players out of their time and pokemon.  If I have multiple pokemon that can stay in active gyms for days, then I should be receiving far more than 50 coins.  Or at the very least, let me remove my pokemon, receive my coins and put them back in.  I propose Niantic changes this, and we bolster the idea of pvp and Gym battles.