Quote from: aurora on Today at 01:50:34 PM

I always use my own entropy source to generate seed.

There is nothing wrong with this, and in fact, it is a good idea in some circumstances. I've done the same for a number of long term cold storage wallets. I generally use the "flip a coin 256 times" method to generate a 256 bit number. From there, you can choose to either convert it to a seed phrase, first by calculating and appending the checksum and then manually converting each group of 11 bits to a word on the BIP39 word list, or you can use the 256 bit number directly as a private key.

Quote from: aurora on Today at 01:50:34 PM

I dont know why but i worry about address collision. Changes of it are very low but there is chance so with my luck I be first one.

There is only a theoretical chance of it happening. Practically, it will never happen. Here is a post of mine from a while ago explaining just how unlikely it is that someone guesses your private key:

Quote from: o_e_l_e_o on June 27, 2020, 08:01:06 AM

Given that most 2FA codes are 6 digits long, there is a 1 in 10⁶ chance of someone guessing your 2FA code.
Assuming an average house lock as 8 tumblers, and each tumbler can adopt one of 10 positions, then there is a 1 in 10⁸ chance that someone will be able to guess your exact house key shape and unlock your door.
Given a standard credit card has a 15 or 16 digit number on it, there is at most a 1 in 10¹⁶ chance that someone will be able to guess your credit card number.
If you use a password manager to generate a long and totally random 16 character password, drawing from the full ASCII 95 character set of upper and lowercase letters, numbers, and symbols, (e.g. CY\u4"=t{rV%;N9S), there is a 1 in 4.4*10³¹ chance of someone guessing it.
The chance of someone guessing your private key is 1 in 1.158*10⁷⁷.

The chance of someone correctly guessing your password, your 2FA code, your credit card number, and the key to your house simultaneously is 4.4*10⁶¹, which is still around 2 thousand trillion times more likely than them guessing your private key.

Quote from: aurora on Today at 01:50:34 PM

Also i dont save 600 word seed i only save few key pairs. Thats all i need

Then using a 600 word seed phrase makes even less sense. It doesn't matter if you have 12 words, 24 words, 600 words, or a million words. The security of any individual private key will always be the same.