I think the manner and reason for the summoning are probably the most important factor. Harry would be unwise to summon Titania anywhere, ever, but he has been known to do some dumb stuff.
However, if he tried to use, for instance, the circle on Demonreach to summon her, that would VERY much be like holding a loaded gun against someones forehead. So then the question becomes how much of a compulsion Harry can put into the summoning, which is something we should ask Jim about sometime. I seem to recall Harry saying both that powerful beings could simply choose to not show up, but I also think I remember there being methods of summoning that are compulsory to the thing being summoned.
Could Harry actually FORCE one of the queens to come to him? Mother Winter obviously did not want to answer Harry's summon because it both hurt and insulted her, but she still showed up, after a fashion at least. I would guess that a powerful enough call could force even a powerful being to show up, especially if you have their true name. After that, you just better pray you have a good enough circle to prevent instant immolation. (like the one on top of demonreach. I am increasingly certain it is a VERY important part of how the warden does his job)
I would guess this is addressed more in the early books when Jim tended to spend more time on the nuts and bolts of magic theory, and I dont remember those books as well.