Is it too easy to cast powerful spells with RPM?

[mlangsdorf]

The problem with regularly limited preparation time is that while it somewhat clips the wings of the super-skilled RPM caster, it makes the semi-skilled and dabbler RPM caster nearly worthless. A less skilled caster - base skills in the 14-15 range, slightly more modest grimoires, and no ritual adept - is struggling to hit 22 on their best ritual (and possibly only 20). That limits them to 60-80 point rituals.

Most of the magical systems in GURPS give massive rewards for achieving effective (or base) skill 20+, and make it no too difficult to do. The easiest solution is probably to limit the maximum skill levels via GM veto - "no, you can't have any Path skills over 19, and you can't have more than 150 total skill across all your Paths" or whatever suits you best.