The distance between each downlight depends on the size of the fittings. For instance, fittings with a 4 inch diameter should be spaced about 4 feet apart in every direction; fittings with a 5 inch diameter should be spaced 5 feet apart, and so on.
Reducing the space between your fittings will increase the amount of light in the room, while increasing the distance will soften the effect. The addition of extra fittings will usually offset the reduced luminosity of mini LED Downlights.
Alternatively, you can install a dimmer switch. This will allow you to vary the brightness of your downlights as the need requires. Remember, if you are planning to use dimmable LED, you will need to upgrade to a Low Load Trailing Edge Dimmer Switch.
As well as general ambience, LED Downlights can also be used to draw focus to particular areas of a room. This is best achieved by using gimbal or eye-ball downlights which can be pivoted. Determine what areas of your room you would like to draw attention to and arrange your fittings accordingly. For example, if you have a lot of wall art, you may want to move your downlights slightly closer to the wall on which they are being exhibited, or group fittings together over a workspace to create stronger illumination in that area.