If you attend Mass once or twice or more in the day and on these occassions you are free from mortal sin and do not receive communion , then this is wrong, you are offering a sacrifice, taking part fully mind, soul, spirit and body, to omit one is to not participate fully and if you have no reason not to participate fully (mortal sin) then you are omitting the return gift from God, infact needlessly rejecting Jesus in the Eucharist. In Ireland they used to offer (not sure about nowadays) continual Mass, one after the other day and night, now the Priest/s received communion on many occassions during the day and night and so did those who attended the Mass/es. It is not a case of being greedy with Jesus, Jesus is a passionate lover, He loves you to come to Him in the Eucharist often, as often as you are able, but at least once a week. If you go more than the stipulated minimum requirement of Sunday, is this also greedy? No of course not. Does Jesus ever say …no I have no time for you, no you cannot let me dwell in you by the Eucharist, you are being greedy with me?..no of course not.
God Bless you and much love and peace to you
Teresa