Frequency of getting shares…

I'm kind of new to this, and basically just playing around with what I have for fun. And what I have isn't much, a 2070 Super and an old 1070.

I started with Nicehash, after which I'm now testing using T-Rex in the 2Miners Ravencoin pool.

But I'm noticing a difference between Nicehash/2Miners ETH pool and Ravencoin. And that is the frequency at which I get/complete shares, whatever the terminology is. With the former, it's a steady flow of shares. With Ravencoin, it feels like I'm getting nothing, or I'm getting everything. As in, sometimes it takes more than 15 minutes until I get a share, and then I get like 3 within a minute.

I just need to know if this is normal.