I remember Sam Gentile when speaking at the Vermont DotNet User's Group saying he wished he had those years back spent working with COM, as technology progressed and COM was no more. (I'm pretty sure it was COM. Sorry, Sam, if I got it wrong.) I felt the same about COM as Sam, after reading 4 Wrox books on the subject before writing my first GetObjectContext.Item() statement. Then I spent my days and nights for a year thinking I was working with the coolest technology EVER! But after seeing a demo of .NET Beta 1 at Comdex 2000 and being told that COM was going away, I was so pissed that I didn't crack open another book or do any after-hours coding for 6 months.
But that's another subject. Now I'm talking about the time sucked away working in goddamn CSS stylesheets. I'm not a perfectionist, but with this site, dbvt.com, for instance, there is a DotNetNuke stylesheet, a .Text stylesheet, and an nGallery stylesheet, each requiring to have the same settings for a uniform look-n-feel. Yeah, I could have consolidated them, but it would reduced overall lost CSS time only slightly.
Any web site requires too much time working with CSS, if you ask me. When I look back on my life I won't regret the time spent coding, studying, reading, working in Photoshop or Illustrator (the latter two have threshold durations where the sucking sound begins, but that's another post.) I will, most certainly, wish I had spent less time dicking with CSS stylesheets.