If one is tracking personal work for billing clients then go for however much detail you like.
As a long time wage slave I tired of the work tracking games, where ill defined tasks with vague goals were broken into shard like piece of overlapping descriptions. Had too many program managers come down weeks after the work was done to demand the timesheets, already submitted and approved, get changes made because they decided it made their numbers look better if they reclassified the work, while also making the workers look like idiots or criminals for mis-charging the programs.
For one program I ended up buying a Palm Pilot to use a time-tracking app because of that 0.1 hour crap. I'd start on a task, then get a call on another one, then get back to the first, to be interrupted by an ad hoc meeting, then be told to work another task. I think the max was 20 charge numbers in one day. I presume there are now iPhone or Android apps to manage this now.