I run two filters in series. From memory, there is a 25 micron pleated filter, followed by a 5 micron wound filter in two separate housings about 20" long and 5" or 6" in diameter. Our water was very silty when I installed them, but a new well produces much better water and I have not had to change the elements in 2 years. Before the new well, water was turbid, but no bacterial contamination. At that time I changed the filters about every 9 months, and the filtered water was clear.
I thought about pressure gauges, but saved the complexity by using Curly's patented simple shower test. If there is enough water flow to take a satisfying shower, the filters are OK. If not, it is time to change them.
According the to the water softener, we use 163 gallons per day. We do not really practice any type of water conservation, since we have both a private well and a private septic. While this seems high to me, it is only 0.11 gallons per minute. We do have a front loading washer which uses less water, but harbors large amounts of black mold. When the budget allows, we will get a new one, hopefully mold free.
The septic was designed for either 0.25 or 0.35 GPM, don't remember exactly, but we are far under its capacity.