Nope, in particular the S300 system can only defend against 6 aircraft simultaneously from one general direction - just like the Patriot. The difference is that the tracking radar can be slewed to the desired general direction - but if you get 2A/C east, 2 north, you can only attack one pair, not both. One of'em is going to do something bad to you.
This is why such systems are not deployed singly - as a singleton it is not just a speed bump, it is a small speed bump.