Most of the places I hunt , parks included , already have chunks of grass missing or dead and small holes dug by critters/kids. I dont worry about killing the grass with plugs unless there is going to be an exceptionally large amount of them , and there rarely is around here since finds are few. You can be so paranoid about what you are doing that it makes more work for you but in the long run , plug or flap , public opinion is not on your side anyway so it makes no difference. There are places where I will cut a flap but not generally. Consider this , if you cut a flap it will have to be bigger than a plug in order for it to fold over and lay flat enough to be searched through , so with all the effort you put into saving the grass you can wind up "looking" like you are doing more damage in the long run. A little 3 inch plug missing or dead isnt anything more than what the squirrels are doing anyway.