Some misunderstand verse 26, which says: "As often as ye eat this bread, and drink this cup," by interpreting it "take it as often as you wish." But it does not say that!
It says "as often" as you observe it, "ye do show the Lord's death till he come." Even Jesus commanded, "This do ye, as oft as ye drink it, in remembrance of me" (verse 25). We do it in remembrance of the Lord's death - a memorial of His death. As you know, memorials are celebrated annually, once a year, on the anniversary of the events commemorated. So we observe the memorial of Christ's death annually. And just as often as each year comes around, we are to "show the Lord's death till he come," by keeping this memorial.
Christ instituted this ordinance on the eve of His death. It was the 14th of Abib, by God's Sacred Calendar, in the very beginning of the day. God starts days at sunset, not midnight. So, later that same day, after Jesus had gone out to Gethsemane, Judas Iscariot led the crowd to seize Jesus. Then He was crucified later that same day, in the daylight part of this same 14th of the month Abib.
By following the example of Jesus in observing this sacred ordinance at the same time He did - the very same time the Passover was forever commanded to be observed - we continue to remember His death, annually, on the eve of the crucifixion.
Some always question the meaning of Paul in verses 27-29 in I Corinthians 11. The apostle is not speaking about a Christian being worthy or unworthy to take it. It is speaking of the manner in which it is done. We take it unworthily if we take it wrongly, in the wrong manner. Once we learn the truth about its observance, and yet take it at any other time than when God says, then we take it unworthily. We take it unworthily if we do not accept the body and blood of Christ. So let's not take this most sacred ordinance to our condemnation, but take it worthily instead!