I use the tuner plugin. I also only run it every other month. It runs from 10PM on the first Sunday of the month to 6AM the next morning, and runs for either 6 or 7 nights. Sometimes after 6 nights it has a couple of hours, or a couple of minutes.
However, for some reason, with the tuner plugin, it seems to take longer than if I were to just let it run straight through.
My parity checks also slowed down when I went from two HBAs for the array to one. But, I really wanted to install a GPU, so I needed to free up a slot. Now that I have switched to 40GbE networking, I can probably remove one of the 10GbE cards, install another HBA and split the array again. HBA prices (like just about everything else) has gone through the roof. I only paid like $240 for the 9400-16i.