"Do those on here who put effort into matching the colour of brake cables, saddles and bar tape and stuff (for example in yellow...) also go for matching helmets?"
"I thought that might be Wilmington's Cow. Then i remembered it's Orange helmet, white bartape and tyres but orange cables and spoke nipples"
Sort of. I'm wearing the helmet all the time at the mo, but it was bought specifically to comply with requirements to wear one at events, when I knew I'd be using the cross bike (the Bealach mor in just under two weeks being the main example).
The bike is black with a little bit of white, but I've got the orange flashes on it (cables and spoke nipples as mentioned by kaputnik, but also QR skewer lever and headset spacers), with a black and white saddle, and some lovely new white tyres have arrived and will be put on tonight.
So having gone to the aesthetic extreme on the bike, I figured if I'm getting a helmet to ride that specific bike mainly, then it might as well match. Hence orange, black and white. With a Molteni cap underneath with the same colours (and for the Bealach I'll be wearing my Molteni jersey - essentially if I'm going to suffer I might as well try to look good while doing so).