Monitoring and evaluation are essential to effective program management. However, instead of serving their true and vital functions, they can become decorations, created externally and tacked onto a project once it's already been designed - usually as a clean-looking table featuring a timeline and a list of indicators to be measured.
Monitoring and evaluation are not the same thing. The purpose of monitoring is to observe your program as you do it, and make sure you're on the right track. The purpose of evaluation is to determine whether you are meeting your goals. These should not be confused. See Evaluation and monitoring in global health for specific examples.
Monitoring, to be useful, needs to be constant. It can be based on very simple numbers. How many teachers/doctors/lawyers/mothers have you trained? Are the trainings still attracting participants? When your master trainers observe trainings, do they still like them?
Once you start getting answers to these questions, you need to use them. That's why it's better if managers collect monitoring data themselves. If participants don't like your trainings, find out why, and fix it. If you're not training enough people, maybe you're not scheduling enough trainings, or maybe you're not attracting enough participants. Monitoring is like biofeedback. Observe. Measure. Make your changes.
Evaluation happens less often. You're not going to see impact in a month, maybe not in a year. Annually is usually often enough for evaluation, and you can get an outsider to do it. The important thing about evaluation is that your team needs to believe in it. If you love your project and are personally invested in it, it is tempting and easy to ignore evaluations which tell you it's ineffective. You need a rock-solid evaluation you can trust so that if it tells you to change everything, you actually will.