There are several techniques that can be used to estimate the time required for the preparation and execution of test cases. One common approach is Test Case Point Analysis (TCPA), which involves identifying test scenarios related to requirements and estimating the effort required to prepare and execute each test case.
Another technique that can be used to estimate the time required for the execution of a particular test case is called "Planning Poker." This is an estimation technique that is commonly used in Agile development and is based on the Fibonacci sequence. In this technique, team members are given cards with the Fibonacci numbers and are asked to estimate the effort required to complete a particular task.
Another technique is called "Three-point estimation" technique which is based on the PERT (Program Evaluation and Review Technique) method, which uses three different estimates for each task: the most optimistic, most likely, and most pessimistic estimates. By using these three estimates, it is possible to calculate a more accurate estimate of the effort required to complete a task.
For preparation of test cases, there is a technique called "Test Case Generation" which is a model-based method that uses a model of the system under test to generate test cases automatically. This technique is particularly useful for large and complex systems and can help to improve the efficiency and effectiveness of test case preparation.
Ultimately, the best approach will depend on the specific project and the expertise of the team members. It's often a good idea to use a combination of techniques and continually review and adjust the estimation process as needed.