On the trades I lose I would only lose a few cents and on the trades I gain I would gain much more by using the trailing stop...this commission free trading sounds too nice to be true, doesn't it? is there a catch I don't know about?
Know the fee the exchange you are using is deducting in percentage. Use it to calculate the total amount of fee that will be deducted from you in each trade.
I have noticed this before. Let me make you a good example
You have $5000 that you are trading with
Trading fee is 0.1%
The fee that will be deducted from $5000 = $5000 x 0.1 ÷ 100
= $5
Assuming you have $3 profit already, once you close the position or converted back to a stable coin, $5 is deducted as fee.
So it would be $5000 + $3 (profit) - $5 (fee) = $4998
Remember that you are also charged for opening a position, or when you converted to an unstable coin for profit.
$4998 -$5 (used to open position or used to first convert to unstable coin for profit) = $4993.
Your $5000 would become $4993 after making $3 profit.
Likely this is caused by trading with too much amount of money and you want to close the trade very fast because of fear not to lose. Trade with the amount of money you can afford to lose and make more profit that would be more than the trading fee deducted before closing the trade.
I thought it was only spot trades that were fee free?
It depends on the exchange. Spot, margin or future trading can have no fee, but there can be some tasks attached to it. Some can even be in form of rebate, in a way you will trade and earn some amount, instead of deducting fee, but those are for VIP on most exchanges.