Many tutorials I have watched say that everything should be made in 'quads' (ie. no triangles, and no ngons).
I think this is mainly due to getting into this habit so that if I make a complex model, eg. a rigged character face, then there won't be any animation issues like model warping or bad occlusions/shadows/etc. (please do correct me if this is wrong, its just what I've gathered from many videos and some books).
So I tasked myself with making a Glock handgun, thinking this boxy shape might be a good starter project. I noticed the corners of the top piece are curved/beveled, so I beveled it on my model.
This is where I got my first problem though, the bevel process created about 3 new vertices on each corner I applied it to, but then this leaves the side of the piece with more than 4 edges (see picture):
In the pic you can see I highlighted one of the small 'edges' the bevel created. So now I can count something like 12 edges in total surrounding that side part.
Is that an ngon? Will it matter? And if its not OK, how should I do it?