Use Thermal Relief in High Current Traces?
For SMT/SMD technology, solid filled pads are no problem, if you use a reflow oven that heats the whole PCB up to the melting point of the solder joints. This reflow oven can be as simple as a small pizza oven (That’s what I use at home for reflow soldering).

But if you try to solder solid filled pads with a solder iron by hand, this can be tricky. 

Edit1:
So your Pcb fab will have no problem when soldering pads embedded in large traces, because they mostly use a reflow oven. 

If you design the traces symmetrical (i.e. both sides of the pad have same trace widths, there will not be a floating/aligning problem, too.