Eating Skills how does it work?

Okay so I am having troubles with leveling my skills.
My 2 leaders are both level 70 and both skill level 4s. Do I have to level lower mobs's skill levels and then feed them to my bigger guys?

A little help?

I have read that using monsters with higher skills increase the likelihood of raising a skill when you sac them. I haven't tested this much. I only did one where I had the monster at a skill level of 2 and it failed. A few sacs later, using a monster w/ a skill of 1, I got my next skill level up. So, it seems that it's not required. Also, my highest skill level on a monster, using primarily monsters will a skill level of 1, is 7. I have no idea what it's like when you get higher than that.

Up to skill level 7, it's kind of a crap shoot. You can reach 7 by sac'ing only skill (1) monsters. You can also level the skills to (2) or (3) and sac, but this might actually end up costing more. After level 7, almost everyone agrees that you need to make skill (4) monsters and sac them to reach skill 8-20.

Thats crazy that it takes 4 skills to move one. How annoying

So to level my Pit agility 7 to 8, I have to make one agility 4 to make it reach 8??