USA Today looked at the February, 2018 shootings at Parkland, Florida. Despite planning and training, seventeen people lost their lives.
Their finding: the plan in place at Parkland was well known and easily circumvented when the shooter set off the fire alarm. Plans need to be flexible, rehearsed and updated regularly. You school needs to ensure that tactics used elsewhere will not be effective with your school plan.
The other lesson is that no training program is effective enough to guarantee another attack like the one in Parkland, Fla., won’t happen again.