Eik I kind of disagree with this. I am not big on using the google tools because most of the time they are too simple and lack sufficiente flexibility. A multipel day task should be just that a task that because of it’s complexity or duration will take several, days, weeks to complete. usually this kind of task will/should be split in to smaller sub tasks with shorter durations and more concretee deliverables. But it is useful to be able to keep track of a high level task that spans several days, even if you have the sub tasks that have shorter more concrete durations.
The current functionality already does what you are asking when you bring up the date popup and mark with your mouse a date rang ein the calendar, this is exactly what legend does.. it creates a recurring daily task with your start and end date delimiting it.
This is Ok, but the multi day task is alternative functionality.