This post will talk about implicit schema used in compile plan and conclude the topic of Name resolution, default schema, implicit.
A compile plan may refer to non-qualified schema object. It needs to record that fact an “implicit” schema is used (Name resolution detect such scenario and default schema is recorded in the compile plan, which is used as part of the plan cache lookup key). Batches with unqualified object names result in non-reuse of query plans. For example, in "SELECT * FROM MyTable", MyTable may legitimately resolve to Alice.MyTable if
Refer to Batch Compilation, Recompilation, and Plan Caching Issues in SQL Server 2005 for expanding on implicit schema impact on query plans. http://www.microsoft.com/technet/prodtechnol/sql/2005/recomp.mspx