I have just come back from proof rolling 770m of sub grade surface on a subdivision, yes some soft areas were found, but will take up in a day or so of dry weather. Some tips in random order,
Tip 1 use sufficient mass to test the surface (approx. 10-12t).
Tip 2 be careful to separate movement of the top 5-10mm from deeper movements.
Tip 3 any movement is generally due to excess water, before advising to excavate and replace, question if it can be dried and recompacted. If the movement is minor allow it to sit for a day or so and see if it firms up.
Tip 4 watch just in front of and just behind the rear wheels, do not allow a roller to be used for the proof rolling.
Tip 5 carry a spray can of paint to mark the soft spots, and it is also worth marking them on a plan recording the area involved if required.
Tip 6 check for services in the area of the soft spots as these can often allow sub surface water to enter a pavement. If this is the cause then work to cut off the water will be required before fixing the soft area.
Tip 7 be fussy as it will let the construction crews know how important it is to ensure that there are no soft spots in the subgrade or pavement.
regards
sc