Actually Matthew, and with all due respect, you are wrong.
Before Vatican II (and this is still the case, as a minimum in the 1983 Code) a religious, e.g. Benedictine, Carmelite, Dominican, Franciscan, etc. usually professed solemn/perpetual vows after 1 year of canonical novitiate and 3 years of temporary vows - so only 4 years total. Under the 1983 Code, the novitiate can be extended up to last 2.5 years, and temporary vows up to last 6 years - at the most!
This stipulation to promote for only those perpetually engaged in the SSPX to major orders is actually required by Canon Law. Canon 995 in the 1917 Code, and Canon 1037 in the 1983 Code.