To what degree do lawyers actually want to track their time accurately?

I used to work a timesheet intensive job (consulting). The quiet rule was log the minimum 45h/w if you like your engagement; log your actual hours if you hate it.

When my lawyer bills me 1 hour, I know it doesn’t actually take him 1 hour. That’s just his rate. This has been my general experience with small shops. Do bigger firms pay closer attention to detail?