As much as it can rain in Florida we also have the extreme opposite of lack of rain in our dry season which occurs roughly between November through April give or take.  We can go for weeks without rain.  During the cooler months this isn’t usually a problem.  Most sprinkler systems handle the lack of rain keeping your landscaping looking great.  But as the temperatures rise and the rains don’t come is when problems will show themselves.  A well designed, properly installed, and maintained sprinkler system will usually keep your landscape green.  But as weeks pass with no rain and temps get into the high 80′s if not higher your landscape will stress.  The two day water restriction schedule was meant to work with natural rainfall to maintain a healthy and green landscape.  When no rain has fallen for weeks problem areas may develop.  Brown spots pop up for no reason or areas of grass stress heavily.  Longer irrigation run times may be the solution but do not exceed your water restriction allowance.  Sometime over watering is the problem.  Too much water can rot roots, invite fungus, bugs, or other diseases.  Or the problem itself is a disease or infestation.  Carefully dig down into the problem area 4 to 6 inches and examine the soil.  If it has any moisture content throughout the sample the problem is not the sprinkler system.  However, if the sample shows very little moisture or is even powder dry then irrigation may the problem.  Sample several locations throughout the problem area.  I believe the true test of any sprinkler system is the hottest time of the year.  Improper head layouts and coverage quickly reveal themselves with stressing or dead landscape.  The other problem I have discovered is the soil content is rarely the same throughout the property.  Even with great coverage certain areas stress year after year.  While trenching in new heads or zones I can dig up sand, clay, loam, buried debris, to mention a few all throughout the property.  The varying soils greatly effect how the landscape reacts to daily conditions.  If you are able to clearly determine the sprinkler system is not the problem then contact a good lawn spraying company.  Most have professionals on staff who can come out and identify the problem and treat it accordingly.