Four sources told the Washington Examiner that Rubio’s protective detail is under severe strain and has been stretched to a near-breaking point by senior leadership. One source provided explicit examples of how resource stretches have led to vulnerabilities in protection. One State Department employee observed that “shift supervisors [on Rubio’s detail] have an incomprehensible workload. They are responsible for all the agents under them, scheduling, evaluations and a preposterous amount of admin work [as well as] performing the actual shift work. They work 6 to 7 days a week. I truly believe this [incident] was the result of incomprehensible strain [the agent] was placed under and, at the very least, [Diplomatic Security Service] owes [the agent] a very fair evaluation of these circumstances in their totality – looking deep into [DSS’s] own role [in what happened].”
I'll comment on the military perspective because it's what I know. Manpower surges (working 12+ hour shifts 7 days a week) are meant to be implemented for days or weeks, not long-term. After a handful of weeks mission effectiveness deteriorates rapidly. People burn out, struggle to focus, make simple mistakes, and become difficult to work with and irritable. Compound that with the stress of certain jobs and it's even worse.