A priest at my parish is leaving next year. It seems that six years may be somewhat standard. Is six years a local, national (American), or worldwide time frame for any given priest in any given Catholic parish? Excluding the bishops and deacons. Our pastor is there for 12 years; I would guess this "double-term" is particular for pastors in larger parishes but again I am not sure.
Canon Law permits a particular conference of bishops to establish guidelines for the length of pastor appointments. But being guidelines, a bishop may make adjustments according to the needs of a particular diocese, parish or even the priest in question.
Do priests have term limits?
Not exactly. Canon (church) law permits a conference of bishops to establish guidelines for the length of pastor appointments. In the United States, that term is six years, renewable for another six years. A pastor may be moved prior to that time, or may be kept on longer, depending on the bishop’s assessment of the pastoral needs within the parish and diocesan-wide. - Clergy Appointments
Any conference of bishops can establish guidelines, but any bishop is free to decide and can move a priest anytime if he needs him in some other parish, or for any other reason.
In Italy there are no guidelines, and my bishop usually moves young priests quite often (about 5-6 years) but when they became old, they usually stay in a parish for a longer time (I think it's for pratical reasons, because it's easier for a young man to move)