I got a puncture in the rear tyre a few days before the Wales weekend last year. I used the string type to fix it. However I wasn't sure how good the 'repair' might be so I took it to a motorcycle shop (that sold tyres) to have a look.
They took the tyre off and when he saw the repair his words were, "That ain't going nowhere". Now, I wasn't sure what he meant, was he not going to let me take the bike away without buying a new tyre? No, he meant it was a perfectly good repair and he would expect it to last the tyre out.
However, when I questioned him more he said a 'proper' internal patch would be a better option, he put one on for me and it's been there since!