6-8% seems to be way to exaggerated for arbitrage trading. The markets in the crypto sector are so tight nowadays that such differences no longer really exist. Even for smaller illiquid coins. In addition, the transfer costs alone from one exchange to another are so high that profits usually disappear. A little more information about your specific method would therefore be helpful.
Such situations are not as common as, for example, a spread of 0.5-1%, but a you must have a big budget and make big turns to earn decent money. In addition, trading commissions and commissions for transfers that reduce profit, there are many nuances.
