That's why if we use% *: with numbers when giving strong passwords, it will take a long time for them to hack their passwords.
Not really. If someone is going to bruteforce your password, then they will likely already being using the full ASCII character set. There's a lot more to a truly secure password than just throwing in a percentage sign somewhere.
I think a manual randomly generated password could act in a more secure way than a generator.
That's incorrect. Human beings are very bad at being random, and when we think we are being random, we aren't. You shouldn't be relying on yourself to come up with random passwords, passphrases, seeds, entropy, or anything else. Password managers such as KeePass, which will generate real random passwords for you, are open source, so no trust is needed.