Kenneth,
As Charles & Jon have stated, you should always use Option Strict On at the
top of each of your source files.
I normally include it at the top of each source file along with Option
Explicit On, so other developers know that this file requires that setting.
For if you attempt to rely on project settings, and copy the source file to
another project junior developers may get confused.
The only real time you need Option Strict Off is when you are using Late
Binding. If I need to Late Binding I would isolate it to one or two source
files in the far corner of my app. As Charles suggested, I have yet to need
to use Late Binding.
Word of caution, Late Binding uses reflection under the covers which can be
expensive at execution time. I normally dynamically load assemblies and
early bind to an interface. The objects that I dynamically load adhere to a
specific interface, allowing me to avoid Late Binding.
Hope this helps
Jay