Software with good documentation is far more valuable than software without.
Software that needs to be reliable will be subject to a code review. Good documentation makes the review go more smoothly, and makes it more likely that the review will accomplish its intended purpose.
Estimation of time for technical documentation and software development
Estimating software development schedules is a skill. The programmer who is going to do the work can figure out what steps they will need to take to implement that feature. And only the programmer can estimate how long each one will take. The nature of software development is that things which seem simple are often surprisingly complicated when we think about all the details.
In engineering, technical documentation refers to any type of documentation that describes handling, functionality and architecture of a technical product or a product under development or use. The intended recipient for product technical documentation is both the (proficient) end user as well as the administrator, service or maintenance technician.