Instead, it took me three years from when I started Romans in 2006 to when I finished Romans in 2009. There were two reasons for this: numerical distractions and emotional distractions.
Early on I spent some time putting together a spreadsheet and planning numbers related to my progress. With as long as Romans is, that makes for a lot of numbers to play with (verses, chapters, dates, weeks, months, etc.), and in the end there was not much value in my spreadsheet and numbers, by which I did not abide anyway. My experience confirms others who say habits are better than goals.
The numbers of verses also did not reflect the diversity of content and length in each verse. Some are short and some are much longer. Some are easier to memorize and some are harder. Some mess with one's theology more than others. Consequently, some days may feel like they are filled with monumental progress of hiding away multiple verses at once, and other days are a struggle to make any progress at all. It really varies.
Note: There is value in restraining—even on good days—how much one undertakes in a single sitting. Over the long term, it can be more valuable to have a habit of daily progress that helps one through the more difficult days, than for a subsequent hard day to feel small in comparison to a day of great accomplishment. Even on good days, taking on too much can also overwhelm the reinforcement step necessary for solidifying what one has learned. It's better to make small progress every day than to make large progress sporadically.
In taking on a project with a minimum duration of 30+ weeks, that makes this an inherently multi-season activity. During that time life happens. Seasons come and go. There are ups and downs. By stretching a one-year project into three years, I was clearly not the model of consistency. Throughout the dryer seasons, though, I was faithful to maintain what I had learn so I could pick up more later. That is very important, especially in an undertaking of this magnitude.
Not every day does one wake up with a clear mind ready to focus on hiding God's Word in his heart. There is only so much space in our heads, and it can be hard to simultaneously fit both (a) resolving people issues, and (b) thinking about the meaning of the Word of God, especially if those two are somewhat unrelated at the time. It helps to be at peace. Keep short accounts in your relationships. “Do not let the sun go down on your wrath” (Ephesians 4:26). Maybe start with memorizing Ephesians or Ephesians 4. Memorizing passages like that is helpful both as a peace-making activity itself, and for having God's Word hidden in your heart for when God's comfort would be helpful in trying situations.
On the flip side of this, memorizing can also be a very emotionally uplifting activity, especially when memorizing certain passages. I have particular enjoyed memorizing Job 41 and Psalm 29 this month. These are some of the clearest descriptions in the Bible of God's raw power. It's been very encouraging and confidence-building.
Despite Romans having taken me much longer than it would have otherwise needed, I was determined to finish it, all the while maintaining what I had learned until I did. In part this may have been motivated by having started and never finished memorizing Psalm 119. (Psalm 119 is still on my list!)
Eventually I finished. The downward slope near the end is more fun. Romans has at least three closing-sound statements (15:33; 16:20, 24; and the benediction). All the greetings at the end indeed made Paul's letter to the church in Rome feel more like a letter as well. It was well worth the effort, and I still maintain it, especially when I'm driving at least 40 minutes at once!