No way. :D I'm debating even using store-bought index cards when I can gather so much office quality paper that is printed only on one side and could be used on the other side as a notecard. (As Luhmann did btw.)

For now, using "fancy" index cards motivate me to keep going but as my practice strengthens and I run out of index cards, I totally see myself switching to good old A6 cards cut from bank statements, bills, single-use office papers and stuff.

(I am the office paper waste up-cycling queen - I cut up used B4 office envelopes to use the back side to fold B6 envelopes for my personal correspondence, I bring home discarded office cardboard to shred and use as bedding in bird cages, in compost or as a fire starter in the fireplace in winter, and I already use cut-up office documents to lower my post-it use at work. :D)