Teams are not working at fully time on project 4

Hi all

I explain my doubt; I have one cyclic task (planification = regular between two dates) (70% of a day time) and the other 30% are dedicated to all projects.

For example, for one ressource, I have 4 projects. So, how can I assign the 30% for these 4 projects?

My solutions are:
- 30% / 4 = 7.5% ressource affected on each project (problem: what's happen if today, I have 6 projects, I need to update all my affectations?)
- 30% on all activities ???

My two solutions are not optimal, do you have a better solution?

Thanks

Any idea?

Any idea?

100% or 30%??? because my bandwith for project is only 30%