GPS precision is directly linked to satellite reception, be it WAAS, Omnistar or RTK.

The satellites are on special orbits but not on geostationary, so they come and go ...

 Trimble has a downloadable software on it's site to use when planning your work that will forecast your reception quality, specially when to expect low signal.

If you are lucky, maybe you won't experience low signal because you will be refueling, filling your planter, eating, or having a well earned break at that moment, otherwise, it is a good move to plan one or some of the aforementioned activities at such low signal times.

While doing a 30H non-stop test of the EZ-Steer about a year ago I experienced such low signal periods but was not aware then of this piece of software. As I started the test, I did have the impression I had a plug and play gear in my hands. I am still impressed of the performance this gear can do, but now know of some of it's limitations.

To avoid frustration, I strongly recommend planning your work with this software application: it will help you save time!