Actually it is very seldom a good idea to try and cover all three readings and the Psalm.
Most Catholics are surprised to learn that the First Reading (usually from the OT), is thematically linked to the Gospel reading. The Second Reading (from the NT) is just a continuous reading through the various Epistles of the NT. It rarely has anything to do with the other readings, and when it does, it is just a coincidence.
When you see a preacher (priest or deacon) trying to link them all together there is usually one of two things going on:
- They are relatively new to the ministry (trying to do too much in too short a time)
- They are relying heavily on a homily service publication
I have attended Mass at two different parishes the same weekend and heard the priest give the same synopsis of all the readings straight from the homily service. While these publications are meant to help the homilist prepare; by simply regurgitating what it is them – almost verbatim – is really just giving the homily that some theologian wrote.
I personally never use them, because the author does not know my parish, or what is going on here.
Better to focus on the Gospel, the words of Christ our True God, and bring forth that message. Perhaps show how the OT reading illustrates the same teaching hundreds of years prior to Jesus.
God bless you all for caring so much about the Word of God,
Deacon Christopher