I have done both. Where I am using a bolt action rifle in one caliber for target or varmint, I still neck size. I don't for big game anymore, especially since my son and I shoot the same caliber (30-06).

I have found some gains in my 25-06 with precision neck sized loads of about a 1/4" versus FL. For deer rounds, I stopped though as sometimes these feel a bit tight on bolt close and I want to cycle the bolt quickly in this case.