>I want honest opinions on this, does anyone use full-blown OOP, n-tier development for EVERY application they write?, if it is required from the analysis.
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>Analysis using UML defines a very strict OOP application, but I feel sometimes it's serious overkill for certain apps.
>
>What I want to know is, do you draw the line at some stage, what if you KNOW that your app is only a one off, and will never grow? Or at least be certain of it.

It is not ought EVERY application to be N-tier.
Everything depend on application; clients; targets, which apllication has.
We define this things in the begining. Choose what tipe will be app - desktop stendalone, client-server or N-tier. After thet create framwork of application ....