We can’t estimate the time for any individual task in software development because the nature of the work is creating new knowledge.
The goal of software development is to automate processes. Once a process is automated, it can be run repeatedly, and in most cases, in a predictable time. Source code is like a manufacturing blueprint, the computer is like a manufacturing plant, the inputs (data) are like raw materials, and the outputs (data) are like finished goods. To use another analogy, the reason Starbucks makes drinks so quickly and repeatably is because they invested a lot of time in the design of the process, which was (and is, ongoing) a complex and expensive task. Individual Starbucks franchises don’t have to re-discover this process, they just buy the blueprint. I’ll leave it as an exercise to the reader to infer my opinion of the Costa coffee-making process.