I've used individual spell development for years, but I'm building a high-level NPC and have run into a gap in the rules. Gaps in a list have to be bought, so for example, a Magician working on Shield Mastery has to pay 1 DP to buy the gap at 1st level (or 4th) to get to higher level spells. This is all straightforward p to 20th level. There are blank slots/gaps, and they cost points to move beyond.
But there are never spells at 21st-24th level, everything jumps to 25th, then 30th, then 50th. These cost more for the spells in those slots, but does the Magician have to pay for 21-24 as blank slots? That seems both excessively costly and counter to the way the original "List picks E" model worked. Does anyone know of a clarification or have experience working with this at higher levels?
(If they do have to pay, then why not just make the 25th/30th/50th costs even higher than they are, reflecting the 1+2+3+4=10 DP cost of buying the always-empty 21-24 slots? Getting from 30th to 50th is going to cost an extra 190 DP if that whole gap has to be bridged!)