My current script is around 200 pages. 18 pages of script equalled to 100 pages of comics so
(my script is super condensed and I don't plan panels and pages in my script)
I've sorted my script into 22 chapters (with all the chapters being 40-50 pages long) and I've planned for 6 volumes. This could change in the future, it depends.
At my current rate, I finish around 3 comic chapters a year, it will likely take 6-8 years to complete my comic. This is also factoring in that I take more than a month off after every chapter.
Tbh I don't know how long the story will be to read! It's not short, but it's not super long either.