Why eight turns is impossible and twelve is excellent
Clearing eight pairs in eight turns would require knowing where every card is before turning any of them. In practice the first card of a turn is often one you have never seen, so the turn is spent acquiring information rather than scoring. Analyses of optimal play with perfect memory put the expected number of turns at around twelve to thirteen for a sixteen-card game, and that is with recall no human has.
So the useful benchmarks are these: twelve turns or fewer means your memory and your luck both cooperated, sixteen is a good game, and low twenties is what most people do the first time on a new card set. Beyond that you are mostly turning cards at random, which is a perfectly reasonable way to play but will not improve with repetition.
The decision that costs people turns
Every turn you face a choice: cash in a pair you are confident about, or turn two unknown cards to learn more of the board. The mistake is a third option people take without noticing — turning one known card and one unknown card, hoping. That wastes the known card, because you already knew where its partner was and you have now spent a turn without collecting it, and it teaches you only as much as turning two unknowns would have.
The clean policy is: if you know a pair, take it. If you do not, turn two cards you have never seen, and treat that turn as pure information gathering rather than a failed attempt at a match. Played that way, most turns either score or teach, and very few do neither.
Remembering positions rather than cards
What has to be held is a mapping from grid position to symbol, and that mapping is easier to keep if the positions have names. "Fox, second row, far right" survives several turns; a vague sense that the fox was over on the right does not. Splitting the four-by-four into four quadrants and keeping a short list per quadrant works for the same reason — four small lists are easier to hold and update than one list of sixteen.
One more thing worth trying: the difficulty here comes almost entirely from how similar the symbols are to each other rather than from how many there are. Switching card sets between games changes how easy the board is to remember more than any change in your concentration will. If you want a genuinely harder game, pick a set where several symbols share a colour and watch how far the turn count climbs.
Questions people ask
What counts as a turn?
Turning two cards is one turn, whether or not they match. Turning a single card and then turning it back is not possible — once a card is face up it stays up until the turn resolves — so the count is unambiguous.
Is the score based on turns or time?
Both are reported and neither is folded into a single grade, because they measure different things and improving one usually costs the other. Turns is the more meaningful of the two; time is there so you can see the trade-off you are making.
Are the cards shuffled properly?
Yes. The deck is shuffled with a Fisher-Yates pass, which gives every arrangement an equal chance. It is reshuffled from scratch for each game, so a layout is never repeated and there is nothing to memorise between games.
Why do mismatched cards stay visible for a moment?
Three quarters of a second is long enough to register what was there and where, and short enough not to be tedious. Cards flipping back instantly would turn the game into a reflex test, and leaving them up longer would remove most of the memory element.