Of COURSE it is ok for testing. It (NT7) usually works quite well for learning how software works, how the entries and exits will go, how the ATM system functions, etc. But you occasionally get a glitch with it, so in your testing regimen you must discard those trades. But in general, paper trading is shit in the sense of the PSYCHOLOGY behind it. You don't feel the pain and glory of the trades when it is fake money. And that is how people get caught up on crap like trading 100 contracts in the ES with 50K in an account.
Never used sim in my life. I've sometimes thought hmm coulda bought here, coulda sold there. Though got rid of that stoopid habit quick.
I do not think, that paper trading is a total shit. It is useful if you want to understand, how online trading works and to build your own strategy. Of course trading with fake money is not similar to the real one, as you risk much more, but in any case it is not bad. Especially if you use trusted paper trading platforms.
You can make all the money you can on sim, but nothing is going to prepare u for the flood of emotions you'll feel when trading live. Confidence is always high when paper-trading. That's also one sure way to tell when someone's faking it online (streamers)....they are generally calm. Controlling your emotions is the single greatest skill you need to master when attempting to trade live....and being on sim only gives an illusion of a false sense of confidence.