Pay no attention to Fudgy and his memes. He has no idea what a sprint is, only what it is not.
You're on the right track with attacking by riding faster. If you take off like a banshee in a Cat4 field they are going to either a) ignore you because you're not a marked rider or b) you're on your own and you better have the stink to pull it off or to get others to join you. If you attack attack attack with no purpose you will be forever marked as the idiot that hasn't got a clue. If you attack late, you better have double the stink because you're not going to get any quarter from anyone.
Do you know what your five minute power is? Have you done interval work where you hit the gas and then go for five minutes? Do you keep track of lap times so you know when to go? We can talk strategy all we want but if you don't know what you are capable of, then we are all just pissing in the wind.