Ridge and hip shingles
The perforations are there so each tab can easily be separated for the cap on the ridge or hip.
I would not use them for any other use except for cap or for your starter row.
I wouldn't think that you would have that much left over anyway, a bundle maybe?
If you need to do additional roofing, just buy the appropriate archi/3 tab or whatever you are using. Keep the hip/ridge for just that.