Two settings, different jobs
A flat brisk walk and a slower uphill walk can both create a meaningful aerobic demand. They also involve different movement patterns and local muscular demands. There is no universal setting that makes one the correct choice for everyone.
Treadmill incline is usually expressed as percent grade, not degrees. A 10% grade means a rise of about ten units for every hundred horizontal units, not a ten-degree angle.
Handrails change the comparison
Holding a rail for support can alter balance demands and how much of your weight you support through your legs. That can be entirely appropriate for the person, but it means the displayed setting alone does not describe the work.
The machine's calorie estimate may not account accurately for that support.
Change one variable when learning the response
If you increase both speed and incline substantially, it becomes harder to tell which change caused the new demand. A smaller adjustment can make the response easier to judge.
There is no need to match a named treadmill routine exactly. A setting that lets you move comfortably and control the intended effort is more informative than an online combination presented as a universally effective formula.
