Can you please give us the ability to enter just hours/minutes or even just minutes without setting the start/end time in a time tracking column. In most cases the start/end is irrelevant, however the time spent on a task (the actual effort) is what is really important. If it could default to today and then have a box for hours and minutes (or just minutes) where we could type in a value?
e.g. This is from a competitor.