2nd Edition DMG page 2, paragaph 6: "Take the time to have fun with the AD&D rules. Add, create, expand, and extrapolate. Don't just let the game sit there, and don't become a rules lawyer worrying about each piddly little detail. If you can't figure out the answer, MAKE IT UP! And whatever you do, don't fall into the trap of believing these rules are complete. They are not. You cannot sit back and let the rule book do everything for you."
3rd Edition DMG page 6, paragraph 2: "You get to decide how the rules work, which rules to use, and how strictly to adhere to them."
5th Edition DMG page 4, paragraph 8: "[This book] helps you adjudicate the rules of the game and modify them to suit the style of your campaign."
4th Edition DMG, page 7, paragraph 13: "Remember that the “right way” to play D&D is the way that you and your players agree on and enjoy."