A long while on my head. Until it starts missing spots. Have to change them out a little more regularly for my neck. Two three weeks of use maybe

Ha! Sometimes, when I shave every day, one will last for a couple of weeks. If I'm shaving a 2 week old beard, I'll need to use 2 disposable razors. All the while using an old toothbrush to clean away the stubble caught between the blades.

I have not use one in years.

I only use disposable ones when traveling. Otherwise, I use Billie.

I have to use a Weed Wacker.

Sometimes months passed. I’m quite lazy with shaving. When I could afford it I bought an expensive manual razor with removable/disposable heads.

Pits and legs. They work for a long time before they have to go in the trash.

Months

I go through 2 or 3 a year

The first time I feel a whisker pull it gets changed, usually takes about 8 to 10 uses.