My buddy Dave in Tucson tried the same fix on his sunken pavers and the mudjacking quote came back at $1,100 for a 12x14 patio, which is nuts when you can rent a plate compactor for 80 bucks. The thing is, pumping stuff under there only lifts the pavers back up, it does nothing about the reason they sank, which is that Phoenix dirt moves like crazy when the monsoon hits and there's no gravel base to spread the load. So you're basically paying to redo the same mistake and it'll dip again by next summer. Ray's corner by the grill dropping 2 inches in 8 months is fast, that tells you the dirt under there is washing out or settling hard, and a patch job won't stop that. Pulling them up sounds awful but the pavers come up easy since they're not glued, so the real work is digging down and doing the 4 inches of compacted gravel like you did. Only shortcut I'd say is worth it is saving the old sand for the top layer and renting the compactor instead of buying one.

The "cold kitchens are the worst enemy of bread" line hits hard. I spent my first two months thinking my yeast was dead when really my counter was just too dang cold. Once I figured out the fridge top trick it was like a whole new hobby opened up.