Share your ideas .
I'm so sorry, I don't know how to pattern inside sketch mode.
However, for me , when I create a sketch, I usually make them simple and not much so detail in one sketch. If you create sketch and make a pattern inside, your sketch will have a lot of constraint symbol and dimension and it is not simple if you have to modify that sketch.
The best way to modeling is, make a simple and clean.
Indeed its better to pattern features than lines in sketcher, but if you need a pattern anyway, I usually draw a centerline at half the desired distance and mirror the geometry around that centerline.
I the geometry is not symmetrical, Im afraid ctrl-c, ctrl-v is the only way.