We use PPLNS reward system on 2Miners. Miners work together to find a block. When it is found they split the block reward based on their hashrate. This system is used to prevent "pool hopping". Pool checks how many shares you've sent from the last 12000 of pool shares and makes the payouts based on that value (20000 shares for Equihash coins).
It could happen so that your hashrate is too low for example if you got just 1 GPU. In this case even if you send shares to the pool when the block is found your percentage could be zero (you got 0 shares from the last 12000). If that happens too often and if it is really annoying we advice you to go mining some coin with low difficulty in SOLO. For example Whalecoin -> https://solo-whl.2miners.com/