Of most Generations, I have both 1 that levels inside its elements and 1 that does outside, so I can compare their development; so far, those outside their level are indeed faster.
I want to summarize my results (so far) soon and present them here; maybe they could be included in the guide? (Just as a small note of course, not taking up too much space; I just think it would be nice as many people wonder if it's a good idea to level them outside their element or not. ^^)

I dig outside of my knuffels element a lot even though most of them are raised in their element since the chance of them hitting food is the same everywhere. It takes a little longer because Lv25 and below can only did 3 times under the wrong element before getting exhausted which can be good because you can feed it more. >w<
You don't get mats this way or much food but the EXP is much more. o___e

Why do level them in their element? If you level them outside their element and let them dig there, you can get food AND mats. ^^

Once theyre at higher levels I want them to be in their element to dig up digging outfits and mats that are only found in their element. o_e
Besides raising them outside of their element is sometimes confusing. My Eleaus Dark gen3 is wind but I accidentaly gave him 2 dark points :<
So now he'll be 98% Max

You're not the only one who does it like that. ^^ (I know someone else who does, too).


Well, you can call me the queen of misskilling, so believe me, I gave them wrong points quite often.

I guess its a risk u should be aware of >XD
I was so careful to. I was estatic when he evolved I forgot he was air x__x . I bought him after Alister (My other gen3 dark) and he shot right past him. Alister still hasnt evolved. X3