PS - if a Pure spell user is trying to develop 6 separate spell lists ... they have fumbled their "Character Creation" roll ;0
the average Pure Spell User has 10 base lists (called A-J, where A-F represent the core lists) and may be interested in one additional open list and one closed list (K and L respectively)
Level 1 - develop 3 ranks each in A, B, C & G
Level 2 - develop 3 ranks each in D, E, F & I
Level 3 - develop 3 ranks each in J, K and L
=> Without overcasting, this progression can be repeated ad-nauseam and ensure that the character always has ALL of his core base lists AND several additional list known to his level ...
This progression also leaves a small amount of DPs for developing PP's, Hits and assorted additional skills.
For Hybrids (K is an Open list in realm 1; L is an open list in realm 2; Hybrids do NOT get bonus base lists unless they "go evil") -
Level 1 - develop 3 ranks each in A, B & C
Level 2 - develop 3 ranks each in D, E & F
Level 3 - develop 3 ranks each in K and L
For Semi's -
Level 1 - develop 3 ranks each in A & B
Level 2 - develop 3 ranks each in C & D
Level 3 - develop 3 ranks each in E & F