First of all is that it will make your trading riskier.

Traders use it when the are losing. But It encourages them to start an opened position with very little amount of money.

Example is a trader that has $500 for trading. The trader can be using just $100 to trade. If he wins, he will take profit and look for a better  coin again to trade with. But if he is losing, the trader can add $100 more to it, making it $200. Also if the trader is losing as the market is against him, he can drive to add the remaining $300. Do not use leverage. Leverage will return it to gambling.

If you are able to make analyses that can make you predict the price you should average, it can help. Averaging will let the mark price get closer to the entry price.

It is very risky but it is worth it for traders that knows how to use it.