Bad mistake. Should have only done one a day.
Risk of getting caught before you finish taking care of business. Better to plan things out and then execute your plan quickly.
Look at the 9/11 terror teams. 3 were executed in a short enough time frame to be carried out as planned. The third was off schedule enough that the passengers were able to block a successful execution, although the passengers were killed while interrupting the plan. And the fifth team completely failed.