Does anyone on here use yield maps?

Back in the day we had very early CaseIH AFS yeild montiors on the combines I drove on harvst in the US. These produced lovely looking contoured maps from what would have been blocks of data. Processing power and data storeage now is a fraction of the cost it was in the mid 90's, but combine capacity has increased hugely, though not as fast, so you're likely to get bigger blocks of data due to the wider headers and higher forward speed. We had a magna scan (i think it was called) about 20 odd years ago. Some guy drove up the tramlines every 24 metres on a 4 wheeler dragging a scanner behind it that was about as wide as a shoe box, this was measuring water holding capacity, iirc. I saw the raw data, that was just a coloured block every few metres, from this that managed to develop a beautifully contoured map. Hmmm. 

By blocks of data, I mean, the machine will take a reading on yeild every second or three, faster forward speed must equal fewer measures per area? Anyway...

What do you do with in the information? Do you use variable rate seed, fertiliser or chemicals? Do you increase in the inputs on higher yeilding areas or reduce it etc?