There was a pet theory he wasn’t backing up his work and a system failure caused him to repeat it from memory

five? ADWD was published in 2011. We're coming quickly up on ten years for the next to last book, no one holds out any hope the last one will ever be written.

It will probably come in a bundle, along with a copy of Half Life 3.

"next to last"

The popular theory on reddit is that he Winds of Winter almost finished around season 5 of the show, but found plot holes (specifically in Mereen) and basically rewrote the whole thing.

That's my hope anyway.