Yamaha DTXpress/DTXplorer/DTXtreme

That groove check is the worst function on the brain.
It was one of teh reasons I went for the DTXpress, My timing slips now and then and playing to clicks has been a downfall of mine for years.  But the promise of tuition from a box is a long way from realisation.

If you actually used the groove check all the time, then your playing would be decidedly less "groovey".
It doesn't take account of playing behind the beat in blues numbers or ahead of the beat to make the track feel more lively.  Basically, it teaches you to be a cold machine, I will not be using the Groove Check again.