Here is a chart that shows the amount of free space remaining after each garbage collection (MIT/GNU Scheme compiling itself, heap size 1935360 words):
It is almost disappointing that the detail is lost when we use larger heap sizes. The charts for the large heap sizes are essentially flat. At large heap sizes, the variations in temporary storage usage become insignificant.
In other words, the number of garbage collections becomes less dependent upon the moment by moment allocation of the program being run and approaches the simple limit of the heap size divided by the total allocation.