A method for generating scan-based test patterns for an integrated circuit design includes, in a computer system, generating a number of current interval patterns for the integrated circuit design in a current pattern generation interval. The current interval patterns can be augmented to satisfy observe needs of a previous interval pattern generated in a previous pattern generation interval. Observe needs of the current interval patterns are stored in association with the current interval patterns. The current interval patterns are linked respectively to P streams of test patterns. The current pattern generation interval is subsequent to the previous pattern generation interval. The method includes simulating the current interval patterns to identify observable scan cells in the integrated circuit design, linking the P streams of test patterns into a single stream of test patterns, and storing the single stream of test patterns in a computer readable medium.