You are correct, insofar as what Loctite says, but reality is highly debatable. There are plenty of machinists and other people people dealing with critical fasteners that have found loctite to work for years on end. Some postulate that the time frame is a liability cover statement. Loctite employees have been known to give longer periods of time. As an example, here's a forum post I read some time back,
"My last job I worked for Henkel, they own Loctite, I worked with the Loctite sales and technical group regularly. One year is the shelf life, they test to 2 years with no more than 90% loss in bonding strength. The rate of degradation accelerates with time. I replace my Loctite every 2 years."
I have Loctite 242 in my guitar shop and have been using the same bottle for ten years. Flows the same, hardens the same. I've not done any testing to prove its holding power. I have some fresh Loctite 242 as well: I'll torque up two bolts with old and new, and measure breaking torque, and report back.
For the cars I'd go 243, that deals with thread contamination better ...
Filippo