How many work hours are needed for ISO 27001 implementation

This really depends on the size of the company and whether a company uses a consultant or not - for example, a smaller company of 30 employees that uses our Toolkit would need ca 6 months for the implementation, and during these 6 months the work breakdown would look something like this:

Project manager would need on average 5 hours per week during this 6-month period
Each department head would need ca 3 man/days during this whole 6-month period
CEO or some other member of top management would need ca 2 man/days during this 6-month period

Here you can find the ISO 27001 Duration Implementation Calculator, so you can find out more precisely how long would it take in your company: https://advisera.com/27001academy/free-tools/free-calculator-duration-of-iso-27001-iso-22301-implementation/