There are 1.3M lawyers in the US according to the ABA. There are 250M adults in the US. I find it hard to believe that this is common (if "pretty common" means more than ~20% of adults?).
But yes I do agree, it's probably a minority of people that regularly use a specific lawyer.
I figure the number of lawyers willing to do such small favors is in the range of 1% to 10% of the 1.3M (wild guess). So if each of them had 100 friends-and-family "clients", it still wouldn't add up to "pretty common".
Also further reduce your number for adults in the name age bracket as practising lawyers.