Having your lawn mowed on a regular basis is best.

Here's why you should keep to a regular routine and mow your lawn when it needs it. Consistent mowing heights allow for consistent nutrients within the grass, helping your lawn look the same throughout. Leaving your lawn too long can block out the sun from reaching the undergrowth and can lead to die off from under.

Why should you not cut grass when it's wet?

Wet grass tends to cut less cleanly, resulting in larger clippings. These wet clippings like to clump together and block up the mower's deck. ... Mowing wet lawns increases the risk of rut damage, since the soil is softer and more slippery for mowers, and the grassroots can more easily be torn out by the mower tires.         

Why should you use a registered lawn mowing business?

Because they will have Public Liability Insurance and Guarantee their workmanship.