A few things that you may wish to bear in mind when planning your project;
- Minimize number of assignments per task to say 1-2 assignments.
- Do not mix Resource Type assignments on common tasks. Split/create different tasks/assignments as necessary.
- Resource assignment (task) durations should be reasonable say 2-5days. Use re-occurring tasks as necessary to split larger single assignment durations.
- Use multiple ‘annual’ projects for long running assignments.
Hope this helps….