Can sight-reading hymns regularly help your general organ music reading skills?
Yes, I think it might, but for people who are struggling with this, my advice is to do it very slowly and systematically step-by-step, taking a number of hymns and practicing 1 voice at a time, then 2 voice combinations, then 3 voice combinations and finally all parts together.
Tony asks if my 40-week Organ Sight-Reading Master Course is with video lessons, or only pdf lessons? He's also interested in the Hymn Playing Workshop and is wondering which course to take first.
Sight-reading course is PDF only, no videos. Hymn playing course, though, is all video content.
For people like Tony, I recommend taking Hymn playing first, it's cheaper, shorter and easier.