The only time I had a 'problem' with NGK was entirely my fault. I found the screw cap could work its way loose over time and, concerned this could cause a problem, put threadlocker on it not realising that said threadlocker acted as a partial insulator

Once I discovered my error, I now screw the caps over a few strands of copper wire which 'locks' them in place.
The bike almost always starts within one or two kicks from cold, maybe three if it's hot.