Because it just doesn't work out, it is not enough to actually get a grip on things before product-anxiety and need to re-order kicks in. It becomes close to 'over' too soon. Inevitably re-ordering would also be all at once;-( 6-month shampoo sets rule, re-ordering is usually a few things in stock-up sizes instead. The standard MP shampoo set is stable and for a good while. Maybe order a LONGHAIRS® BTN Duo Beginners Kit...Add a non-member SURPRISE BASKET in any denomination for adding spice to your DUO!!!