Questions about evolutions. How many are usually released and how frequently?

My last ultimate team was FIFA 23. So I wasn't familiar with evos. After playing FC26 for over a week, I understand it more now, I've done a few evolutions, 2 of which I regret. One being Tillman, as I literally did him when his cornerstones card was released, now my teams changed a bit so I'm using Nmecha, whose much better and I could've evo'd him instead. 

My second regretful Evo is a Korean striker from the Turkish League, who I put into striker's rise, but because of the cancel bug in training camp, he is now capped at level 3. The final Evo would've completely changed the card and he's just sitting in my reserves. In hindsight, if I put the striker I use and love, Njinmah, in striker's rise without cancelling, then that would've been great. But he's no longer a silver now and is 75 rated, because of some Evos I put on him.

So because Njinmah has 88 pace and is Gold, will it be unlikely for an Evo to release for him?

I've also wasted a couple Evo upgrades on Solet, who I don't use and I could've put on someone else.

My main question is how frequently are Evos released and how much variety is there to fully upgrade different cards? Have I messed up wasting some Evo upgrades this early on?

I am aiming to basically make a full Evo team, as I've seen that's what people had on FC25, but so far I've been a little disappointed with the lack of Evo upgrades released daily. I know it's only the start of the game, but since I'm new to this and made some poor decisions, aswell as being affected by a bug, I'm a little impatient to get Evos for my main ST's and CM.

Please, anyone that is an expert on anything Evo, give me some advice. I have been looking at futbin, so no need to mention that. Thank you.

I've added a picture of Njinmah, alongside my team if that helps.