There are several reasons to have the float function with your rear remote valves.

For top link use:

The main reason is for mowing in rough or steep terrain. Having the top link in the float mode allows the mower to travel to more extremes for mowing over an edge and down to pond banks or up a bit on steep banks as examples.

Having the top link connected is always the safest thing to do. Some people use a chain to allow full movement of the cutter, this is not a safe condition to work in and should not really be done. A lot of 3 point mowers have a built in bracket that allows for more than normal movement, while that works well for slight angles, they typically do not allow the mower to pivot enough for steeper grades. This is where the float function really shows its benefits.

For side link use:

The float function allows for an implement to follow the terrain instead of the tractor.

Examples of this would be using a 3 point landscape rake in an open field. You want to rake up material on uneven ground. By putting the side link in float mode, this allows the rake to follow the ground and stay in contact with the ground, gathering unwanted material.

Another example is when finish grading-smoothing at road intersections. As you go around a corner at an intersection, the camber of the road often changes, kick the side link into float mode and the implement will follow the grade instead of the tractor.

These are a few examples of why you want to have the float function with your rear remote valves, not a huge thing, but very nice to have when the situation presents itself.

Fit Rite Hydraulics