yes you can be too long depending on your arrow rest (release shooters in general).

generally most people use 4" with carbons in a straight offset with a launcher or prong style rest. If you shoot a fall away you can shoot 4" or 5" with helical, heck you can even shoot 4 fletch if you want. This is for mechanical or fixed blade heads.

for mechanical heads some people use nothing but straight fletch and you will find anything from 3" to 5" fletch being used with them with the vast majority using 3" or 4" .

With fatter diameter shafts such as aluminum 2315' s or 2512' s as examples you will mostly see 5" offset straight or helical. since the shaft is fatter you have more room to get better fletching clearance out of most styles of arrow rests. you do see a fair share of 4" on aluminum anymore.

Hope this helps you out some.