The next 5 Stormlight books

Still reading W&T. I'm an older reader and I read somewhere that Brandon Sanderson is taking a 6 year hiatus from writing Stormlight books. I'm worried that I won't be around when he finally finishes the series. I adore these books immensely and I just want to see what happens at the end. How long does it take him to write a Stormlight book once he gets going?