Actually you bring up a good point here - k2tog is a right leaning decrease and is generally used at the left edge of a piece. The corresponding or 'matching' left leaning increase is SSK or SKP (sl 1, k1, psso) and is used at the right edge. This makes the decreases 'lean' toward the center. When a pattern calls for decreasing several stitches evenly across a row, most people use k2tog, you don't have to 'match' them.
sue- knitting heretic