User blog comment:SolarMist/Limit Breaking and Skill Levels/@comment-17760674-20141221184210/@comment-17760674-20141221223934

If I'm understanding you correctly, then your summary is correct. (I think. I'm getting all of this info second-hand xD)

"So even with just skill 19 at lv.70 would be max skill 25 daemon at lv 85 with only 4 duplicates,won't we?"

Not quite sure what you're asking here, but I think the relevant info would be that the skill limit at level 85 is skill 23. As far as I know, you can't have a daemon with skill 24 or 25 without the daemon being max limit broken, because the skill limit will prevent the skill from going higher depending on the max level.

"Or to be said skill 19 -> 21 and 20 -> 22, using first duplicate after lv.70 isn't it?"

Not quite sure what you're asking here o.o;

"And if we already maxed skill 20 at lv.70 only need for 3 duplicate + 1DLR?"

You've got it backwards. You only need 3x DLR and another duplicate. You would use DLR for 70 -> 75, 75 -> 80, and 80 -> 85, and each of those brings the skill level up by 1 (because of the extra levels) to meet the max skill level of 23 at level 85. Then you use your duplicate for 85 -> 90 to go from skill 23 to skill 25.