My approach is to keep two versions:
1) The Contract schedule that more often than not cannot be used for management at the site as the Contract Schedule is frequently lagging revised logic and activities necessary to manage the project. In most of our jobs the client never approve revisions to the contract schedule on time for it to be useful for site management while the project finishes with no court claim.
2) An Optimistic schedule that is based on aggressive estimates of project parameters we use for project management. It will include those activities not yet in contract schedule but that are required to manage the schedule no matter if approved or not. It will not include allowance for rain days as it is not a good idea to plan short term activities assuming it will rain before it happens. It will not include contingencies as it is not a good idea to include them within this schedule because of Student Syndrome and Parkinson's Law. The Student Syndrome is tolerable for a few, non-critical tasks. But when the number of critical tasks affected increases, then whole schedule will be at risk. Parkinson's Law is the adage that "work expands so as to fill the time available for its completion".
It is necessary to target for some early completion in order to increase the probabilities of meeting contractual requirements, otherwise you will be targeting for failure. The period between planned completion and completion date or Terminal Float is owned by the contractor under the contract and is mandated in some European contract models such as the NEC to the point if there is no terminal float shown the schedule might be rejected.
USA practice is the opposite, terminal float is usually prohibited and interpreted as a reduction in contract time; therefore we have no other option than to make use of Ghost Schedules if we want to increase the probabilities of meeting contract dates. This schedule does not needs to be shown to the client [1]. This schedule will include contract schedule activities plus a few additional not yet included, in this way we keep actuals of these activities that while not in the contract schedule are actually happening. We use this version as the basis for updating the Contract Schedule as it will include all activities within both versions and synchronize updating using Spider Project capabilities for doing so.
[1] Ghost Schedule- In a significant case concerning Ghost Schedules and their use, Jackson Construction, Inc. v. United States.7 the U.S. Court of Federal Claims stated that a contractor is under no obligation to advice owners of its planned early completion [Ghost Schedule].