I usually do two pages at once (because it'll be easier to figure out how they will look together). So for both: Penciling 3-5 hours, inking 3-6 hours, screentone: 2-4 hours (I dion't usually color), lettering: 30mins to 1 hour (since I already have the script). In total for two pages it ranges about 8 and a half hours to 14 hours or between 4-7 hours each
That being said, even though the industry standard is about a page a day, I think how fast you finish a page totally depends on the page itself +style. Plus, how fast or slow you do a page will change throughout your life. Back in highschool I could do a page in 2 hours, but it didn't mean I was any better than someone who takes longer (like me now)