I've developed a "show-me-where-it-says-that" mentality over the years when dealing with this kind of issue. So below is the exact language from the USA Cycling site pertaining to upgrades:
http://www.usacycling.org/
USCF Road Upgrades
Guidelines and Notes by Category:
5-4: Experience in 10 mass start races that meet the criteria in the table below (qualifying races).
Local Associations may also establish policies where upgrade credit is given for taking a sanctioned rider education clinic.
4-3: 20 points in any 12-month period; or experience in 25 qualifying races with a minimum of 10 top ten finishes, or 20 pack finishes with fields over 50. 30 points in 12 months is an automatic upgrade
3-2: 25 points in any 12-month period
60 points in 12 months is an automatic upgrade
2-1: 30 points in any 12-month period
60 points in 12 months is an automatic upgrade
USA Cycling may add additional requirements for upgrading at their discretion. Any such changes shall be made available on the website.
Qualifying Road Races for each category
Category
Class
RR
Crit
Field
Experience
5 – 4
Men
15 mi
10 mi
10
10 races
4 – 3
Men
25 mi
20 mi
30
25 races
Women
25 mi
15 mi
10
25 races
Junior
25 mi
15 mi
10
25 races
3 – 2
Men
50 mi
20 mi
50
Women
40 mi
15 mi
20
2 – 1
Men
80 mi
35 mi
60
Women
50 mi
20 mi
30
Note: 4-3 upgrades, and 3-2 upgrades, and 2-1 upgrades mention the 12-month window. Cat. 5 to 4 upgrades do not mention any time limit.
Also note the language about credit given for taking a "sanctioned rider education clinic".
Also note that the specific term is "experience" in 10 mass start races. That means you have to start, but not necessarily finish, 10 races. You could conceivably do 4 or more races in one weekend and Cat. up in less than a month if you really wanted to. (Not commenting on whether that would be a good idea or not....).
Bob