If a senior software engineer is asked to develop an internal technical training, can she apply the estimation and planning techniques (related to software development) she knows?
What development methodology do you use? Agile tends to not be documentation-heavy, whereas waterfall methods let you develop documentation while developing the program (since everything is already known). In the past I've written what I thought people might need, handed it off to someone that has never used the program to see if they can use it easily. If not, I fill in the holes or clarify items. Then I push it out.
It depends what estimation and planning techniques the senior software engineer knows.
As a software developer and an instructional designer, I have seen both sides of the coin. Traditional instructional systems design bears a close resemblance software development methodolgies because it leverages the same systems analysis concepts. It must be considered, though, that the development of training and the development of software address solutions in two different domains (i.e. human learning vs. software applications). Senior software engineers and other subject matter experts need to take that into consideration.
There are many rules of thumb in the instructional design literature that can be used as aids in estimation and planning (see, for example, "Estimating Training Design and Developing Time and Costs".) These averages can then be refined by empirical evidence and the knowledge of subject matter experts. The instructional design process is not a closed system, so any industry specific tools that can be used in the analysis and design phases will make the training program that much better.
The most important thing to remember is to focus on the learning process. Use some sort of systems approach in order to make sound decisions, resulting in a learning process that is both efficient and effective.