I bulit a wrap around deck, did I screw up with the spacing?

I bulit a wrap around deck, did I screw up with the spacing?

My house is on peir and beam with the dimensions of 48 foot by 24 foot with tan shingle roof and hardy board siding. The long section of my house sits west and the short sits south, so I built a deck the entire length of the west ( 48 foot)and it wraps around the entire length of the south end (24 foot). I ran three rows of piers (concrete cinder blocks resting on 16 x 16 x 3 concrete footers). I ran the the beams using 2 x 6 treated boards every 6 foot (used deck screws and steel hangers) that attached to a header that is 4 x 6 treated beam (and yes I know that was overkill, but I wanted the deck to last). I used 2 x 4 treated boards as joists 20 inches on center (secured with deck crews and steel hangers). The span of the deck is 5 foot 10 inches, thats why I ran the OC at 20 instead of 16 inches). I also ran a set of piers to the 2 x 4 joists with 4 x 4 treated wood piers fastened to a concrete footer. Now the propblem I'm worried about is I bought 5/4 x 6 x 12 number 2 treated decking spaced 1/4 inch apart. It'll hold right? I got concerned because of the 20 inch OC measurement I used. The scerws are all galvanixed and the deck is roofed with brown sheet metal. Do I need to crawl under and start adding extra 2 x 4 joists, because that will be impossible since I also cross braced the 2 x 4 joists together. My Dad (who built 5 houses, said I overbiult it and it will be fine).