English Pennies from late 1700's question

Why do these seem so poorly struck? I purchased a set of well circulated coins a few years ago that were from colonial times...there was one Connecticut in the group and the other pennies seem to be all English. I thought maybe because of the poor quality on some of them that they might be Machin Mills but the dates don't match up. Compared to other coins of the times these seem to be just poor quality overall, with the detail being lacking, planchet problems, off center strikes, etc.
Is this common? If so were there just quality problems at the mint? Just curious really.
K
Is this common? If so were there just quality problems at the mint? Just curious really.
K
ANA LM
0
Comments
The only other pennies of this period would have been tokens, which were usually of good quality and did not resemble coin of the realm, and fakes. Most of the fakes I see though are halfpennies, although I freely admit to not collecting the pennies and not being very knowledgable on them. There are probably more fake "halfpennies" in circulated grades than real ones from this period, and many of them are of very poor quality.
World Collection
British Collection
German States Collection
Roman emperor Marcus Aurelius, "Meditations"
Apparently I have been awarded the DPOTD twice.
K