Oh, a good one'll stick around for decades if you take care of it-way longer than plastic or even rubber handles! I have a wooden-handle knife my grandpa gave me, and he used it for 30 years before passing it to me. Now I've had it for 5 years, and it still works like new. The key is how you maintain it-wood needs a little love, but it pays off.
If you skip maintenance? It'll last maybe a year or two. I had a friend who bought a wooden-handle knife and never oiled it-after 6 months, the handle cracked from dryness, and he had to throw it away. But if you wipe it down after use, dry it, and oil it every 3-6 months? It'll be your toolbox staple for years. My grandpa's knife has a few scratches on the handle, but that's just character-no cracks, no warping, and the blade (stainless steel, of course) is still sharp.
Usage matters too. If you use it for light DIY jobs (patching nail holes, spreading wood filler once a month), it'll last even longer. If you're a pro using it every day for heavy work (drywall mud, scraping paint), it might last 5-10 years-still way longer than a plastic handle, but you'll need to oil it more often. My carpenter friend uses his wooden-handle knife for detailed woodwork 3 days a week-he oils it every month, and it's been 8 years with no issues.
The only time you'll need to replace it is if the handle cracks beyond repair (which is rare with care) or the blade gets too dull to sharpen. But even then, you can sometimes replace the blade-some wooden-handle knives have removable blades. Overall, a well-cared-for wooden handle putty knife is one of the longest-lasting tools you'll own. It's not uncommon to see antique wooden-handle knives at flea markets that still work-you can't say that about plastic!
