I love Flex Time (Polyphonic) in Logic Pro X – it saved my off-beat playing a lot of times. Of course it's very interesting to move markers right on the hits (aka. quarter note hit, 8th note hit, 16th, so on) but sometimes I just have a pattern played using only 8th notes (quavers, whatever you call them) and sitting and snapping each off-beat 8th note to grid becomes not so interesting. So... is there any automatic approach to snap all off-beat markers perfectly to closest on-beat grid position? Of course this doen't apply to triplets, quintuplets, sextuplets and some other tuplets because they can fall on a tick instead of even beat.
For the most part, you should do it yourself, as sometimes you want to leave a certain transient as it is, because it might create a vital artifact that can easily spoil the sound in a place, where it is snapped to grid. But in most cases, you can use quantization and then listen while correcting the transient that are quantized off (this happens especially with triplets of any type, mostly 16th note triplets though) or those that sound bad due to created artifact.