The purpose of developer testing is to speed up the development of completed software of an acceptable level of quality.
Which leads to two caveats:
- it is perfectly possible to do it wrong, so that it actually slows you down. So if you find it slows you down, it is very likely the case that you are doing it wrong.
- your definition of 'acceptable quality' may differ from that of marketing. Ultimately, they are right, or at least have the final say.
Software that works is a specialised, niche market, equivalent to high-end engineered hardware made from specialist expensive materials. If you are outside that market, then customers will no more expect your software to work reliably than expect their shirt to stop a bullet.
