Try the training notebook ( thetrainingnotebook.com ) I’ve been using it for over a year and it’s been great! it’s not perfect it could be a little faster and more program lines but it’s the best one out there so far. I use it on my iPad Air and it’s been great no mo paper work for me it’s all on my iPad
Try the ‘3 in 1 Timer’. It has an interval timer, stopwatch and countdown timer. You can save presets for when you run your sessions.
It’s pretty easy to use. I use it to run group classes, and train individuals. Big buttons for my giant fingers. ha. No complaints.