I'm not even sure the USAF teaches the 70-degree method anymore. I don't have my "usb stick" with me so I don't know if it is still in 11-217 (Instrument Procedures).

I can tell you that just about everyone I've flown with (military) used AIM / ICAO holding entry techniques.

To answer the OP's question, no it doesn't matter how you enter holding. But if you go outside the holding airspace, which unless you're a terps expert and you're sure of what you're doing, you will either anger ATC or you could hit terrain. Unless you have a compelling reason to go against AIM / ICAO, you probably shouldn't.