Focus rails for macro

I have a question for all you guys, and ladies, who are taking the excellent macro shots I see here regarding focus rails.

I have just purchased a Canon 100mm Macro non IS but may be turning it in for the IS version. My question to all you fine macro togs, do you use focusing rails? If so, which ones, and how well do they work.

I was taking some pictures using a tripod, and getting the pod as close as I wanted and make fine adjustments was a little difficult. Am wondering if the rail is a big assist.

with a rail, you preset your focus and move it back and forth on the rail to "focus"
(or at least thats always how I've seen them used)

I dont use one. I shoot handheld 90% of the time.

the focus rails are obviously going to be an asset only in the case that you have a stationary object and for stacking. In the case of bug hunting, I don't think you'll find any benefit in it - and maybe even the opposite.
What kind of macro do you want to do?
I have a no-name one from Singapore (UN brand), but the sky is the limit. There are some from novoflex which are highly considered and even some automatic ones which will automate the process according to your set criteria.

Probably some bug chasing, but also flowers etc...I just got the lens so will wait awhile and see where the lens takes me in my picture taking.