When the Episcopal Church first went to the Revised Common Lectionary a few years back, I was not all that thrilled with the weird Track 1/Track 2 choose-your-own adventure style Old Testament reading options. I thought that more or less defeated the purpose of a lectionary read in common.
I have found I actually like the option, especially the Track that pretty much takes a book and lets you read through it in relative order. This go round, it is Genesis. I have gotten to write sermons twice in a row now on coherent story lines.
It works that way with the gospel, usually. With the three year cycle, we pick one synoptic a year and go with it, pretty much in order with some exceptions. John is read during Holy Week and other parts, so he gets interspersed in there as well. The New Testament epistle readings are hit or miss sequentially speaking. The lectionary folks try to make the epistle and gospel have the same theological theme, again in theory.
I have found preaching a book in sequence has its advantages. You can build on themes and do not have to completely start from scratch and be forced to give relevant back story every single Sunday.
The lectionary does give variety, but I am beginning to wonder if the variety is done at the expect of ever getting into any homiletic depth over a span of weeks. One can certainly go over board and beat a biblical book to death, preaching on it every Sunday for weeks on end. I am not advocating that because I believe Christians need to engage the whole bible.
But, that having been said, weekly snippets simply do not cut it either.