It depends on a few things:Breeding question.
I'm aiming for a 31 / x / x / 31 / 31 / 31, and I'm using two x / x / x / 31 / 31 / 31 parents, as according to the breeding guide this yields the highest chance of getting what I want. Is it better to soft-reset or mass-hatch?
1) whether or not your female parent has the right nature already (if it doesn't, then yah, definitely lock onto the right nature and SR).
2) whether or not you're going for a specific ability. If it can have more than 1 ability and you want a specific one... lock onto the right ability and SR.
3) # of steps for egg to hatch. Generally if it's many steps, I'd mass-hatch because I can hatch more eggs in the same amount of time even though only half of them will have the right nature. Other people have different opinions on this probably.
4) Not usually an issue most of the time, but how well your parents love each other (i.e. how fast they produce egg) should be considered. If it's a long time, then probably better to SR also.