I would like to make a difference between self made Wills where you copy some one else’s Will or draft your Will all by yourself versus having a guided approach. When you create a self made Will, chances are there will be mistakes or you could overlook something.
A common mistake a person inexperience in drafting their Will is giving everything to say A, and then later specify an individual item, say a watch to B. Another mistake is getting the percentages or fractions wrong and leaving some portion not distributed. For instance, you give 50% of your home to your spouse, 30% to son No.1 and then forgot you have another 20% left over.
Writing a Will without having a residual clause is another common mistake. I’ve seen quite a few such Wills. With this mistake, what happens is that your estate is considered partial intestate i.e. your Will does not cover the whole estate. This can happen when you acquired additional assets but did not write them in your Will. A residual clause would cater for such assets.
These are pitfalls if you copy someone else’s Will or if you draft the whole Will yourself especially if no one take a second look. However, with Wills that are written with software whether installed in your computer or online, the software is designed to catch such mistakes. Good quality software will prevent you from writing such mistakes even if you deliberately try to do so.