My last big payout was 24k demon + 16k golem + 7k Warlock.

now i invested 24k demon + 16k golem + 7k Warlock + 4k griffin + 5k dragons + 2k Wyvern  ( spend more resource than what i received in last big payout).

i am getting medium pay outs like 4k dragons or 6k necros once in a day or two days.

i use BG calculators for medium payouts like 4k dragons or 6k necros.( you guys are talking about these payouts). 

but there is a big payout (like 15k dragons or 15k necros & 5k golems, etc). 

i got my previous big pay within a month. but this time, there is no big payout till now.

Then you are on the right path. No one can guarantee when you will get a payout but if your resources are full and your bank is full you have better odds of a larger payout.