As to helmets wearing out in 3 or 5 years.
Both points of view could be valid...
A street helmet that is put on and off several times a day and worn for longer periods of time, will experience more inside wear and the interior padding will become looser on the head than a race only helmet that is used 5 to 10 times a year and put on and off a lot less often.
But on the other hand the helmet actually does not wear out,,, it just can wear inside to a point that if the fit becomes loose,, get a new one with a more recent Snell Cert.
As a rule, for my Race Helmets I get a new model every 5 years and the old one has no wear and is in great shape,,, I figure that in 5 years the safety and technology must have improved so I take advantage of that.
To each his own on replacement intervals and cert dates,,, as long as you are within the guidelines now of SA2005 or newer,,, if your helmet is 5 to 6 years old and you like it.. than so be it.
The inspectors look for the Snell Cert tag and general condition of the helmet when presented in tech.
Have fun and be safe this season.
Charles