Did Great Scouring really last over 100 years?

Battle of Thessala (where Fulgrim slit Guilliman's throat) is said to be a part of Great Scouring. But it happened in 121.M31 which is 107 years after the death of Horus (Horus Heresy ended in 014.M31).

Does it mean that Great Scouring lasted for at least 107 years?

If yes, then it sheds more light on how destructive/violent Horus Heresy was (it took Horus 9 years to do all the Heresy, but Loyalists needed >100 years to chase off all the Traitors).

It creates potential for another big book series. It also gives authors plenty of time for some Perturabo's character development and hopefully retcon his ascension to Daemon Prince and also turn Iron Cage to Imperial Fist's crushing defeat.