My first proper ancient coin was an SMHA campgate. Its quite early in Constantines Reign. I've seen hundreds of them, at least a few engraved by the same man, but I havent found the match yet. This is much more like the normal heraclea campgate... Mine is actually a bit of an odd design similar to other mints in the region. Whilst looking through many campgates from many mints, I've spied some awfully similar dies from different mints. I reckon they had a celator exchange program of some type.
Also, design features crop up many years apart. Its clear that groups are taught by a senior and the style continued. Its a very fluid transition. When major design changes come into effect, the transition is much faster - but thelarge bust Constantines do look a lot like the more modern Constantine II (hair and jaw line are maintained). But, interestingly, the left facing bust is completely different to the right - clearly, the celators were trained to engrave dies in a single direction and couldnt switch.