I always leave the dwell stock on all the markers i had owned. No reason to mess about when i know it will shoot without problems all year round.
Once you start changing settings from stock, ie warm weather, then come winter you will need to adjust settings again.
Some players like to tweak to get the most and squeeze every ounce of performance out of there marker, but you will need an understanding of how and why they work better, there is no magical number, every marker is different.
Those who have less knowledge or just want to go out and play, then stock settings = bomb proof !