T/P flies in a groundtrack that repeats every 10-days and goes as far north and south as 66° latitude. This means that it samples approximately 400000 points over the ocean every 10-days. Compare that to ship measurements, moored buoys, or tide gauges. However, there are still gaps in the data, which means that the image in the earlier slide is based on interpolating real measurements to a constant grid, then smoothing them and plotting them graphically and assigning colors based on the heights.
Lines are T/P groundtrack and dots are locations with more than 24 ship measurements in 3 years.