Pretty high on the list of Things I Won't Do is using galvanized, or Phillips, deck screws. Live is just too short. Epoxy-coated square/Robertson drive screws only. That's based on doing 6-8 decks a year for 20+ years. If epoxy-coated square drive screws aren't available, I'll order them or wait until they are.
One deck--I helped build it back in the '90s, and we-re-decked it for the second time 2 years or so ago-- was built (against my protests!) with galvanized Phillips screws. 'Cause, you know, "them fancy screws are expensive". No: expensive is the time it took over the first two years when the screws rusted, and broke or the heads stripped when we tried to tighten them after the boards shrank, plus the extra day it took tearing the old decking off when it was time to replace it. The second time we used "them fancy screws". No problems tightening the boards after the usual shrinkage. When I re-decked it the second time, it took an afternoon for me to strip the old decking.
One deck--I helped build it back in the '90s, and we-re-decked it for the second time 2 years or so ago-- was built (against my protests!) with galvanized Phillips screws. 'Cause, you know, "them fancy screws are expensive". No: expensive is the time it took over the first two years when the screws rusted, and broke or the heads stripped when we tried to tighten them after the boards shrank, plus the extra day it took tearing the old decking off when it was time to replace it. The second time we used "them fancy screws". No problems tightening the boards after the usual shrinkage. When I re-decked it the second time, it took an afternoon for me to strip the old decking.