Suppose you release a new game and make no changes to it from the time that it's released. Your only marketing effort is to submit it to the main shareware and gaming sites.

How long would you say you have to wait before you see the average sales of the game. Is it obvious right away how it will do? Or does it hit it's stride later? If later why?

And a related question...

If you release an update to a demo that improves conversion by +100% (twice as many sales) How long do you have to wait before you can see a difference?

It all depends on how much information is available. For one, having more downloads automatically yields that much more information. Likewise, having a higher conversion rate yields more information (more clients decide to buy -> more data coming in).

Should I throw in a number I'd say one should wait about 10 sales (plus the average delay between download and sale) before being able to have a very rough aproximation of the conversion rate. This means the higher the download counts _and_ the conversion rate the easier it is to measure the results of changes to the game.

So a pretty good but poorly marketed and not very polished game which generates 30 downloads a day and has a conversion rate of 0.5% may take months before drawing the line and calculating the new conversion rate, while a game which gets 500 downloads a day and has a 2% conversion rate only requires a few days or a week.

I believe getting out of the blind spot where it takes very much time to measure results is a very important milestone in the development cycle of indie games.