While the method works, there are a few considerations. First of all, to take advantage of small spread to make decent income you will need a lot of fund. Second, since the fund needs to be readily available at all times, the money will need to park there and you have tons of fund getting tied up at the exchangers. Third, you will need to be constantly monitor the price movement because these thing can shift very fast as there are also other traders keeping watch of the movement to take advantage, not only you. Unless you can find a bot to trigger you.
I'm not disputing whether the method works or not but obviously these obstacles have to be overcomed.
Easily overcome via bots on both exchanges you own that'll trigger when the preset parameters are reached.