Sometimes, it is possible to perform a bit of multitasking. A task may require attention every 5-10 minutes, in which time another similar task may be performed. - Both tasks are billable.
An example is server maintenance for a client (or several clients). Installing and configuring updates, software, etc. - Often such tasks are "fragmented" and may be performed in parallel.
It would be great to be able to have an option in Settings to switch on "Track Multiple tasks simultaneously", which enables several stopwatches in parallel. - This saves me from having to manually tracking it and manually adding it to the timeframe.