Strassen's algorithm is rarely used: its primary use, to my understanding, is in matrix algorithms of more exotic fields than reals or complex numbers, where minimizing multiplies is extremely useful. Even then, Strassen only starts to beat out naive matrix multiply when you're looking at n >= 1000's--and at that size, you're probably starting to think about using sparse matrices where your implementation strategy is completely different. But for a regular dgemm or sgemm, it's not commonly used in BLAS implementations.

The more advanced algorithms than Strassen's are even worse in terms of the cutover point, and are never seriously considered.