On an average, how much time do you take to write a good copy...

The short answer is "it depends".

For a client project, it's typically 40 hours of work for writing, editing, proofing, and polishing. Unless it's a rewrite, I'm writing everything from scratch and charge accordingly.

I usually do 4-7 rounds of revisions too. I'm probably one of the slowest copywriters for hire, but my clients are always happy with the copy I deliver, so that's what matters most.

If it's my project, then it's significantly less because I already know the niche being written for and the product from doing the research as part of product creation. I can spend less on my own projects because if my own sales letter bombs, I'm upset with myself but it doesn't damage my professional reputation. If time permits, I just head back to the drawing board to figure out why it tanked. If it's something like a one-time only teleseminar, then I don't worry about the copy's performance after it's been used for my info-product business.

If it's a client project that tanks (which is rare), then I continue to work with the client to get it on track.

Hence, the original answer of "it depends".

Hope that helps,

Mike