Track for pricing, not for surveillance
The useful output of time tracking is a realistic billable ratio and better estimates. Neither requires logging every six minute block.
Use three buckets
Billable client work, business work such as sales and admin, and everything else. Record the bucket at the end of each half day. Two weeks of this gives a ratio you can actually trust.
Estimate from history
Before quoting, look at how long a similar piece of work really took, including revisions. Then add a buffer. This single habit prevents more underpricing than any rate negotiation.