The actual space available will dictate the system used.
In my bilge there is a collection sump that has feeds from the two showers and the aft sink, as those are the grey water sources that can't be drained out above the WL. In that sump I have a Rule 2000 with a float switch. In the first few years of owning this boat I checked that sump regularly, but as I came to know it, by sight, smell, or sound, I found that an annual look at it was all that is required, unless there was a problem. That sump is fixed in place, with its top open to the bilge in which it sits, so if ever there might be a high water event in the bilge, it will act as an overflow pump out for the bilge, at least to bring the level down to the height of the top of the sump. Otherwise, the float switch brings the sump level down to the height of the present float switch's limit of just over an inch, in a space just big enough to house the pump and float switch. That size, given regular use of the showers, gets enough flow to keep itself clean enough so there is no smell.
In the early years I rotated that pump out to the main bilge area, but more recently I have had such good service out of all my pumps that there hasn't been any need to do so. That good service hasn't extended to the float switches, as last summer saw replacement of switches at all 3 pump locations.