My deadlift, bench and overhead press have increased as much in the last 5-6months as in the previous 3 years. I had only just joined this forum and I don't think it is a coincidence! My squat will eventually make gains too now that I am finally hitting depth.
I think everyone should try and train above 80% of their 1RM for at least a year. In terms of what is hopefully a long time lifting, 12 months is not a lot. If they find that getting stronger is not for them, they can go back to their old routines. However, not too many people who lift weights will be opposed to getting stronger, especially when they see the noticeable size increase!