The pitch of your LED panel again should be determined with an understanding of the quality of the visual communication you wish to portray.
We know that a higher resolution is determined by the closeness of the individual LEDs such that a lower pitch (LEDs are closer together) results in a higher resolution screen because there are more LED dots per square metre or cabinet to display your content.
Having said that, the pitch is relative also to the viewing distance. The further away from an LED full-colour sign, the less “dotty” the sign will appear thus a lower requirement for a high resolution if viewing distance is greater.
This is especially true of outdoor LED, where longer (and higher) distances allow the pitch to in fact increase. Typically outdoor LED may range from P8 to P12 for general built-up road-side signs in a city. But it is not unusual to have P16-P30 for large high-rise LED displays, or large bill-boards along freeways that have considerable distance from the road. These will usually be bigger in size too.
Size of the LED panel (consider longer viewing distances) provides the “WOW” factor. Advertising on larger panels looks impressive and will improve an advertisers desire to appear on the display.
Where larger text message fonts or branding statements are required (never too many words per slide), the LED panel should be made bigger. More images on static slides are possible with larger signs. The images or pictures will say more than the words.
Certainly the sign size should increase as distance becomes greater and higher. Outdoor passers-by, particularly motor traffic, can only glance at short intervals, so statements must be short and read easily from a greater distance.