The majority of systems seem to have either 5 or 12 angles. The only common thing I've seen is that #1 is normally a forehand attack to the head. It can be diagonal (as in Doce Pares, Balintawak, Lameco, Inosanto kali, Modern Arnis, Rapid Arnis...) but some systems, notably Pekiti Tirsia, have it as a horizontal shot.
Sometimes you learn new sets of angles within a system (Some Doce Pares groups have angles for long range, close range and knife). I trained in one arnis style that started with 5 angles, then 8, then 12, then 20. Also systems that are composed of several styles have different sets of angles. I have seen at least 4 sets of angles taught by Dan Inosanto during seminars (over a 15 year+ period).
That said the first style I trained in, although descended for Doce Pares, had 7 angles. (Standard first 4 - forehand to head, backhand to head, forehand to body, backhand to body - then a straight thrust, palm-up thrust and palm down thrust)