I do not find any progress bar for a task.
I think it is very useful.
Thank you for the suggestion. We might consider adding a feature such as this in the future. Feel free to vote on it: http://todoist.com/Vote/showProposal/2/
Do you have any suggestion on the most efficient way to track progress in a task (independent of time spends on a task) at this point based on the available features or third party apps?
I tried Toggle and it only works if the progress tracking is based on time which is often not the case for me.
I can't come up with something specific so far. Besides Toggl, the only suggestion that comes to my mind is using labels. For example, tagging tasks as @30min, @1hr, etc. or @start, @process, @almostdone :-)
Also, creating sub-tasks would allow to divide a big task into a few steps and then complete them one by one and see how many steps left to do.
We will consider adding some option for tracking task progress in the future.
Have a great weekend!