TUL is the simplest application for tracking your Time Under Load (TUL). It's designed to match perfectly for those following single set to failure workouts.
Simply select the exercise, press start and away you go.
TUL provides a simple graphing capability to display your progress in a particular exercise over time. It also allows you to configure your desired optimal Time Under Load target range.
Beyond that, TUL does exactly what you want and nothing more. No messing around with workout routines, tracking sets, recording reps, etc. Just tracking your Time Under Load.