People can play however they want. The reward system is random is really just a numbers game. The more engrams you decode, the more likely you'll hit the jackpot. But if you want the best rewards, from my perspective, that's done via the weekly nightfall. I did it 3x this week and got 2 exotic weapons, including Ice Breaker, and 7 legendary shards. If you aren't a level to do that, then perhaps hooking up with a friend who can carry you would help. The lowest reward I saw on all the runs was 5 coins.