Magnesium is an interesting one, because all sorts of muscle things (cramps, restless leg syndrome etc.) can be caused by, or helped by, both high and low levels of magnesium. It seems to be something that needs to stay within a certain band for muscle control to work properly.

Anecdata +1 but taking magnesium every now and then has done wonders for my leg cramp issues.

Did you take the magnesium also just before bed or morning?

I have the same issue as above. Right before bed is typically suggested for bruxism, etc. Magnesium has also been shown in a study to improve sleep quality, though I don't remember the exact mechanism.

I might have an absorption issue though. Magnesium salt topical spray (less costly than pills) helps intantly unclench my neck/shoulders, and theres extant literature on that being an effective method of administration.

I don't take it on a schedule.

I only take it when I feel a twinge in my calf. I figure I'm probably deficient in magnesium or something. Even if it is a placebo, it seems to work.