One of the main reasons that people hire estate planning attorneys is to create estate plans that are at airtight enough to minimize the possibility of challenges.
The reality is that for any random person, the overall likelihood of a Will being contested are relatively small.
Perhaps the biggest thing that can make a Will contest more likely is the value of the estate. The more money there is to fight over, the more likely it is that people will fight.
The possibility of winning a contest to a valuable estate makes the expense of the contest more likely to be seen as worthwhile.
Will contests are also more likely, if family members do not get along for other reasons. People who are at odds over other issues, often find that they are at odds over the divisions in the estate.
This is especially true, if people are surprised by the details of the Will and do not think they received as much as they deserved.
An estate planning attorney can advise you on creating an estate plan that fits your unique circumstances and could help prevent a challenge.
Reference: Financial Advisor (Dec. 15, 2017) "Strife After Death."