I would like to expand on my previous post.
The number of days allowed at temporary gateways (outside the country of your permanent gateway) is limited to 30% of your contractual days per calendar year. The standard contract is 200 years per year, resulting in a maximum of 60 "contract days" that can be spent at a temporary gateway. This is all due to EU social security rules.
The thing that is important to understand is that OFF-days at a temporary gateway will not count towards the yearly allowance. But days on tour before and/or after using temporary gateway will count. Basically, when you start and end a tour out of a temporary gateway, all tour days will count. If you start at your permanent gateway and end at a temporary gateway, only the last day of that tour will count towards the annual allowance. If you start at a temporary gateway, but end at your permanent gateway, all tour-days will count, except for the last day.
As our work rhythm is usually 6 ON and 5 OFF, you can do 10 full stays at temporary gateways in a calendar year. You can surely optimize it, by playing with the above mentioned rules, but it is definitely a step back from what we had before.