The size of the minimum rate must be chosen equal to no more than 1/2000 of your bank. Why 1/2000? Because you will have a margin of 9 losses of the generated number in your chosen range and balance balance for the 10th rate, after which about half of the balance remains.
If you mean betting with 50% win chance, then even 1/2000 of your bank can be not small enough. Losing 15 times in a row is a common thing, and over 20 times in a row can happen too. The thing is that if it was possible to say that you are insured against losing over 20 times in a row while betting with 50% win chance, many people would just be rolling on dice sites instead of mining.
Applying this type of technique I have lost up to 30 times in a row, often with a lot of balance, what happens is that the Provably Fair somehow determines what your game pattern is, and according to that applies strategy in the same way, when it happens this kind of thing, so you can confuse it in some way is to play randomly because there comes a moment that while you are doing random movements you are playing in the hands of luck and what happens, when there are random movements, the system no longer finds any pattern and it starts to win, it's simple logic, I've been playing for a long time and I've discovered this way, many times I changed to 2x, 3x, 5x, 7x, and betting with different amounts, that's how I've managed to be more successful.
There is no guarantee that you will always earn profits in this manner though, but I found it to be much better than depending on something like the Martingale system.