This is false. The "years" or "days" associated with indulgences were years or days of "canonical penance". "Canonical penance" was a pentential practice in the early church that involved a temporary excommunication and a mild sort of "shunning".
The Catholic Church has never defined any dogma concerning the passage of time in purgatory.
At least your author, in this post, manages to distinguish between indulgences and temporal punishment, on the one hand, and confession, justification, and eternal punishment, on the other.
This is still polemic, not history. (Ministers write polemic. Historians write history.)
On that note, I'm hoping to gain a plenary indulgence this week. I'm heading to 7 AM Mass to see if I can corner Father into hearing my confession. He seems intent on the usual 4-4:30 Saturday Confession.