So there's no point in looking?
You can't calculate the % of illegitimate children who appear/ don't appear in a family will unless you do a lot more research beyond the word "illegitimate" which was used only sometimes in wills. In the example I gave for Charles Joughin his grandmother wrote only "She left to her Daughter Margt's son Charles Joughin Thirty shillings when he will go to a Master Trade". Before seeing this will Charles was unplaced on extensive Joughin charts.

Another example was John Creech, one of the illegitimate children of William Creech, whose 1795 will was fought over by his half-siblings (including another John), and was a key resource in sorting out this family - but the word "illegitimate" never appears.

Sue