It comes down to visual preference. Do you like the grip in the alignment line or perpendicular to it? I would generally prefer the latter, maybe in specific cases the former. It just depends on what seems most intuitive to you. Otherwise, it doesn't matter.
For example, if you would align a lavatory block against a wall, i would like the grip to point at the wall, so i would set it to perpendicular.
But if I would place a car along a curving road, i would like the grip to point in the direction of the road, so i would use tangential.
Best regards
Kasper Wuyts
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