Why it is harder
With draw three, two of every three stock cards are hidden behind the top one. You have to cycle the whole stock to reach them, and each cycle changes which cards sit on top.
Turn 3 deals the stock three cards at a time, so only every third card is immediately available. The layout is identical to classic Klondike; the difficulty comes entirely from that stock, which is why the win rate drops sharply.
Play Turn 3 SolitaireWith draw three, two of every three stock cards are hidden behind the top one. You have to cycle the whole stock to reach them, and each cycle changes which cards sit on top.
The waste order stays fixed unless you play a card from it. Playing one card shifts every later group by one, which is the single lever you have over the stock — use it deliberately, not by accident.
Exhaust every tableau move that turns a face-down card before you touch the stock. A stock card gains you one option; an uncovered column card often gains you several.