What factors would you consider while deciding on the frequency along with which you would report progress to (1) senior IS management, and (2) customer management?
A main factor to consider while deciding the frequency of reporting to anyone is how long the definite project is; evidently, when the project takes only two weeks, a monthly reporting cycle is not going to be of much utilization!
Assuming slightly longer project duration, though, then reports ought at the least to be given at the key milestones, while important deliverables must be finished.
For reports to the consumers as internal or external, reports at important milestones may be adequate However, the project manager will wish for have a regular forum for meeting customer management and increase any issues which have arisen onto the project so, when the milestones are a long way apart, perhaps a monthly reporting cycle may be suitable. For a very quick-moving project, this may be better to have a brief meeting when a week just to concentrate on the major issues.
IS management will almost certainly need more frequent reports, say once a week. These must, though, be as succinct as possible and concentrate onto the main successes and problems encountered throughout the last period or anticipated throughout the next one.