Pastor Englebrecht:
If I recall correctly, the one year (historic) lectionary connects better with the collection of Luther's sermons and those of other Church Fathers.
Me:
Why should this matter?
Pastor Engelbrecht:
The three year series gives you more of the Bible as a whole.
Me:
Agreed.
Pastor Engelbrecht;
However, I tend not to preach whole pericopes but just a verse or so at a time, rotating through Old Testament one year, Epistles another year, Gospels another year and even spent most of a year on appointed psalms. I think this approach would give variety in either series.
Me:
I have often stressed the “connections” in the three readings. The are not always there, but often they are,
Pastor Engelbrecht:
Also, I plan an entire year of sermon topics at one time, choose a particular verse as the focus for each sermon, and select a particular dogmatic or practical topic that flows from that verse as well. That way I can see the whole of what I'm teaching that year and manage the variety and repetition. It's a lot of work upfront but pays off the rest of the year.
Me:
I have never been able to plan beyond the next liturgical season. Congregational, local and world events figure in my planning.
Pastor Engelbrecht:
For next year during the Sundays after Pentecost, I noticed some natural opportunities for sermon series in the readings. For example, for three or four weeks the readings lent themselves to the topic of Christology as a series.
Me:
The 3-year cycle allows us to focus on one of the Synoptics.
Pastor Engelbrecht:
We'll repeat the sermon hymn each week …
Me:
An excellent idea.
Pastor Engelbrecht:
…and give a more sustained and comprehensive treatment of doctrine rather than exegesis in those sermons. I think this approach will give both me as a preacher and my people as learner's something fresh to experience in the "dog days" of the long Pentecost season.
Me:
During the Pentecost season, I often moved another “festival” - commemoration of a saint - to a Sunday, for variety and a chance to touch on history and the saints, biblical, historical and “modern.” (We have such in the ELCA lectionary.)
Pastor Engelbrecht:
Lectio continua in the three year series makes it handy to preach series on a particular book. E.g., in a recent year I had a sermon series on Ephesians. I don't think the one year series allows that. However, I had a colleague complain recently about the lectio continua on John 6, which became difficult for him to keep fresh for so many weeks in a row. That's a different challenge with lectio continua.

Me:
And much of various kinds of sermon planning, to “work” fully, means pewsitters need to be there each week, rumps in pews, ears turned on, memories of last week easily accessible. Count your blessings if you have such a situation.