Yes. In fact, I do it (sorry for using your materials as reference).

However, you have differences in rare materials. For example, have a lot of golden creowns meanwhile I have less in comparison to other rares.

So, I suppose rare materials come randomly.

It is reason why sometimes I asked you about the most scarce materials. I cannot take my materials as a whole reference.

I think it may vary for each user. for example you have trouble with Golden Crowns, while I struggle with Angel Feathers, Books of Light or Fire Orbs. I'm sure you noticed some of my rares are already free, because I have more than 500 of them, whereas I still struggle with some other rares. Plus I sell my mats, and often people need the same mats, so for example I get asked for Angel Tears by 3 people and from 50 I go down to let's say 10

Yes. I am sure you have more info than me because you sell materials and you know the needs from others.
So, if many users ask for the same material it means that it is more difficult to get or it is a key material used by Firn in their quests.
In addition, just say that Earth rare materials are most easy to get (but not some Earth average materials like Green Candle, Groundsels, Saffrons and Cherry Blossoms). I think all are Earth, sorry if not.

I wouldn't say that materials from a particular element are generally easier to dig out. I think it's pretty relative. It matters how many knuffel you have that can dig in a particular element. If you have 5 Earth knuffs maxed in Earth, they will have more success of finding Earth rare mats more often than any knuffel that has been maxed in two or more elements (including Earth, for this example). If you have 10 Darkness knuffs, all maxed in Darkness and 5 Earth knuffs maxed in Earth, it is only logical that you will dig up more of the Rare Darkness mats and not Earth rare mats.
For example I have little Fire knuffs, (I evened it out a bit, but still) and for this reason I'm really struggling with Fire mats, generally speaking (not with all of them though).
But an other user may have a completely different situation.

Another factor might be that the rarity groups of materials probably have in-group rarities as well, that's why for most of us it is hard to get the Groundsels or Cherry Blossoms, even though they are Average mats and we happen to dig out more Green Diamonds instead

I feel like I complictaed it too much ;>_>

No, no memo, you have not complicated it. Let me know that you have explained it very well.
I will take in consideration these factors. Thanks.
Just for your info: I just have 1 of each knuffels (from the beginning to now). So not duplicates and consequently, no more 100 leveled knuffels for one element that for another one.
And just for this reason I though that all kind of materials should come to me in equal amounts.
Another thing is that I try to dig daily in a different element, except if in a quest and I need to replace some specific material.

Good to hear that it was pretty clear :)
But the fact that you have one knuff for each Gen, doesn't mean they have always been on level 100, so they had smaller success in digging from the very beginning, it's not always the same for a new knuffel. Sometimes they are very lucky and dig up something at their first try, but other knuffs don't dig anything (or considerably less than other knuffs of similar level) until they reach higher levels.
Plus as you might've noticed, some elements are more popular than others, so we have more Generations of Light and Darkness knuffels, which probably means you have more Darkness and Light knuffs than other. So it's not like you have equal number of each element, plus they are also on different levels as well. that's also something to consider

And even though the materials have specific rarities, I still think most of them are just random somehow XD

All you say is absolutely correct.
I have 118 knuffels, and just 16 are not in 100 level.
As knuffels are in 17 generation (17 gen x 6 elements = 102 knuffles) plus special knuffels.

Lol, I completely forgot about the event knuffs XD Plus the Darkness and Light knuffs from beyond Gen 17 huh, that's quite an arsenal, an army even

lol...
An arsenal of knuffels, many leveled to 100, digging every day... and the results are less than 100 rares.
Maybe we will need a ton of knuffels...hahaha

Well, I also have less than 100 rares, so yeah I don't have as many knuffs as you do, but also I dig in each element every day.