Reliability of Last-Minute Flights with Points?

Sorry for a novice question, but I'm trying to plan a trip from Northern CA (SAC, SFO, OAK) to Amsterdam or Prague in early July.

I'm looking to spend only 30,000 miles each way, and with the trip being less than a month away, the only good deals I found were from JFK to AMS for 30k miles and from BRU to DCA for 30k points.

I did a search for SFO-AMS for June 8th, and found that the more "last minute" the booking is, the more likely the flight will be 30k points.

Has anyone employed such a last-minute approach to score a deal? If so, did it backfire or work out well?

Thanks in advance!