Kreinestja...your experience is absolutely typical. Block is notorious for bad holding and if you get there too late....the moorings and the decent anchoring spots are gone and you have to hope for the best.
If Block were on my regular itinerary I would invest in an oversized
FORTRESS anchor and use the mud angle setting for the best holding. I would have it on a short chain/nylon road for shock absorbtion and leave the
CQR down below or sell it on e-bay!