Constant repetition serves to free the worshiper from the actual words of the liturgy. They become familiar with the words, what is said and where it is said, and are then able to focus on the meaning of the words. This then leads to a personalizing of that meaning. Each element of the liturgy can then be used as a platform from which to personally approach Christ.
The Lord's Prayer best illustrates liturgical methodology. To get the most out of the Lord's Prayer it is best to consider each phrase in its own right, drawing out its meaning and then personalizing it. So "forgive us our sins" becomes "forgive me for my constant failure to faithfully serve you Lord, and in particular..............." Once the prayer is known off by heart and its meaning understood, the worshiper is able to use each phrase for personalized intercession. The mind simply locks onto the phrase and runs with it. So then, when each element of a liturgical service is remembered and understood, it is possible for the worshiper to pack their approach to Christ with a full range of personalized adoration, and to do that in unison with their fellow believers.
The repetition of each element of a liturgical service also enables children and those with limited intelligence, to participate at their level and to slowly develop their depth of understanding and involvement. Thus liturgy affirms our unity in Christ: there is neither old nor young, wise nor foolish.
For a meaningful involvement in a liturgical service we need to know off by heart the elements of the service and be willing to use the sense of each element to personalize our approach to the throne of grace.