I've pretty much always carried it with me. Once in a while, I'd leave it in a side case. Never had a problem, but then, I never wanted to risk an expensive helmet, either. (Oh, O.T.: In my former home state of Kalifornia, it's NUTS to trust your helmet, or even your dang bike, to be there an hour after you leave it unattended. It's straight 3rd world in many parts of Cali, which is why I'm not living there anymore.🙄😖)
More off topic:
Lol, I've only been on a couple of rides since I bought my bike last fall (it's been a cold spring, and I just haven't been mentally "ready" to commence regular riding yet). On my second ride, I put the helmet in a side case while I went into eat lunch. I could have taken it in with me, but it was more about trying out all the new "toys" with the bike. Well, when I went out, it was cold, starting to rain, I'm standing in the parking lot, and the dang thing won't open up. I've lubricated everything since then, and I'm still not certain what exactly went wrong. I've had problems opening the cases or separating them from the bike, something I never experienced on my previous BMW's. I was thinking that it might have to do with understanding the central locking system, but can't imagine why my key wouldn't open the cases. Testing them further is "on the list" of stuff to do on the bike.
It's LEGAL to ride without a helmet in Idaho, but I really didn't want to do that, on the way home. It took me 15 or 20 minutes to finally get that helmet out of there. NOT fun. It'll be a while before I put anything I really into those side cases, trusting that I'll be able to get to it. The new 49L top case? No problem. So, I think it may be lose tumblers or something like that with the locks.
So, my new helmet will go where I go. I like it too much to just give it away. 😁 (If I ride with the 15 yr old Nolan, however, it'll probably be sitting on the tank, HOPING someone relieves me of it, so it stops tempting me to use my favorite old standby.) 😏