Maximum carry (to me) doesn’t just mean one back cast and one forward cast. The problem with back shooting on your final back cast, is the lack of options. If you aren’t happy with the back or forward cast, you can’t pull it back if you have gone over your carry limit. This is why I aim to cast at least 10 cycles at a certain point to really dial it in. How do I measure the carry? On some of my practice lines I’ve put some marks at every 10’ (starting at 50’) to get a rough estimate, but I use electrical tape and the long tape measure to mark the point where the line will fly it’s best when released. I also have some shooting heads I’ve made from old lines (fantastic idea from a great fellow caster). They aren’t for casting, they are for practice, and it’s fixed, so you know exactly how much line you are carrying. By the way, head length, + haul length + how much line you pull away from the target is how you work out how much overhang to use, oh yes, and release timing. Later release timing means you need to add more.
The carry exercise is my favourite drill as it’s measurable and visual. You can spend hours on it trying different things, and that’s what I did today. I imagined skewering my back cast target with the rod tip, which made a noticeable jump in line speed. You end up with the rod tip pointing at your target. I spent a lot of time working on this until I was happy I ‘got it’. After the practice session I had a go at blasting out some casts with my best being 125’ with the MED5. Work on that carry!