My experience has been fruit pretty much gives up all its flavor in 14 days. Some fruits it does not hurt to go longer in secondary but really doesn't add much.
The seeds themselves for fruit with seeds on the outside or small seeds readily available can give off some pretty harsh flavors if left too long. See the chart below (5 Gallon batch)
Cinnamon to taste just pull it when it hits the flavor profile you like.
Many on this forum would argue this is not enough fruit but for me works pretty well in these quantities.
10 Days
Raspberries Blackberries - Cranberries
Mild Fruit Character 3 to 5 lbs
Medium Fruit Character 6 to 8 lbs
Strong Fruit Character 9 lbs or more
Strawberries
Mild Fruit Character 5 to 7 lbs
Medium Fruit Character 8 to 10 lbs
Strong Fruit Character 11 to 13 lbs
14 Days (Could go longer if you want to.)
Blueberries, Sweet Cherries (Pitted) Pears, Apples
Mild Fruit Character 5 to 7 lbs
Medium Fruit Character 8 - 10 lbs
Strong Fruit Character 11 lbs or more
Citrus Fruits (Lemons, Limes , Oranges)
Mild Fruit Character 5 to 6 lbs
Medium Fruit Character 7 to 8 lbs
Strong Fruit Character 9 lbs or more
Sour Cherries, Peaches, Plums (Pitted)
Mild Fruit Character 4 lbs to 5 lbs
Medium Fruit Character 6 to 8 lbs
Strong Fruit Character 9 lbs or more