Your earning frequency is dependent on Share Tracking - the mechanic behind Cryptomining payouts. While your computer is hashing for six hours straight, you may submit a different number of shares during each 15 minute payout period. This is due to the luck involved with Cryptomining. This results in your earnings varying during each payout. Over a longer period of time, such as a full day, or 7 days, your earnings should stay on average the same, providing there are no changes in the Cryptocurrency markets that could impact your earnings.