Yes, it"s perfectly fine to leave the date field blank. When you do so, the data will be filtered for the entire available time period ("All time").
Considering the limit of 15 filters, can I create 15 filters per survery or 15 filter for all my account?
I want to filter the data of a multiple-answer question in such a way that -
none of option 1 or a combination of option 1 responses should be filtered out
How many filters can we have on Data filter per license?