The Old Testament is roughly three times longer than the New Testament, but as the Bible contains 'progressive revelation' it is best to spend equal amounts of time in each Testament. So, in the three year cycle you will read the whole of the Old Testament once, but you will read the New Testament three times.
The reading schedule also has a special order. The books have been linked together in a way which, it is hoped, will reveal the progress and the distinctive message of the Bible.
The Old Testament is read in time-period blocks. It is easy to get lost in the Old Testament as the time line constantly doubles back on itself and it is often difficult to know where the prophets fit into the story. This reading schedule tries to keep things together a bit more but not 'verse by verse' as some other schedules attempt. For example the book of Job has no mention of the Law or the Levitical priesthood so Job is read after Genesis. That doesn't mean it fits in exactly after the story of Joseph but it is roughly in the same time period.
The New Testament time line is much easier to follow so here things are done a little bit different here. The four gospels have been separated from each other so that the earthly life of Our Lord Jesus continually mixes with New Testament truth. The goal is to see the New Covenant (or Testament) revealed in the life of Jesus Christ and expounded in the letters. The New Testament readings start with the books with more of a Jewish background and this gives the link with the Old Testament.
The actual order is: Matthew, James, Hebrews, Mark, 1 & 2 Peter, Jude, Luke, Galatians, 1 & 2 Corinthians, Romans and then the other letters of Paul. Towards the end the schedules takes you through John's letters and then his Gospel.