Here is a group workout I do with 800+ high school recruits / candidates at Naval Academy Summer Seminar. My goal is to teach them some strategies to improve on their entrance fitness test as well as the Naval Academy fitness test:  Plank, Pushups, 1.5 mile run - taken every semester.

Warmup
100-meter run or 20 jumping jacks or jump rope, 10 push-ups, 10 squats
200-meter run or 20 jumping jacks or jump rope, 20 push-ups, 20 squats
300-meter run or 20 jumping jacks or jump rope, 30 push-ups, 30 squats
Light stretching throughout each set, focusing on arms and legs.
Core Exercises
Sit-ups and plank pose will be tested as part of the Candidate Fitness Assessment for admission to the Naval Academy and at the Academy each semester.

The CFA consists of the following exercises:

Kneeling basketball throw
Pull-ups
Shuttle run: 120 feet (4 x 30-foot runs as fast as you can)
Crunches two minutes
Push-ups two minutes
One-mile timed run

Crunches/Situps are still tested on the CFA, and sit-ups will be tested on the Navy SEAL/EOD/Diver PST if you're interested in that career path.

Once you get into the Naval Academy, you will be tested with the plank pose for time and cadence push-ups (up and down in two seconds). (Note: The cadence push-up is for the Naval Academy only and not a Navy-wide test.)

Crunches: Focus on a pace of 20 repetitions in 30 seconds
Flutter-kicks 20
Crunches 20 in 30 seconds
Leg levers 20
Crunches 20 in 30 seconds
Scissors 20
Crunches 20 in 30 seconds
Stretch stomach

The reason why we focus on a pace for crunches and sit-ups is to prepare for a two-minute test. You need to learn to maintain a sustainable pace, because most people fail this test by starting off too fast in the first 30 seconds and then failing to match their performance in the next 1:30.

By focusing on a pace of 20-25 per 30 seconds, you can find yourself in the 80-100 repetition range in a two-minute test. The extra hip flexor exercises are a fun addition to the workout to give it more of a Grinder PT feel.

Add PT Reset Exercises to balance out front-side pushing and core/hip flexor work. These exercises should be part of transitions or cooldown periods.

PT reset:

Rev push-ups 20
Birds 20
Arm haulers 20
Swimmers one minute
Death By Push-Ups! Plank and Push-Ups (New USNA and Navy Test)
Stay in a push-up "up" position or plank pose for 10 minutes. Do not drop your knee, but you can shake out an arm when in a side plank position. Every minute, do a step of the push-up pyramid, decreasing by one each minute on the minute.

The workout looks like this:

Minute 1: 10 push-ups. Stay in a plank pose for the remainder of one minute.
Minute 2: Nine push-ups.
Continue in "up" push-up position or plank pose nonstop for 10 minutes, increasing the push-up repetitions by one each minute:
Minute 3: Eight push-ups
Minute 4: Seven push-ups. Keep going to minute 10 and one push-up. That equals 55 pushups and 10 minutes of plank. We call it Death by Push-Ups, but it is more Death by Plank.
Advanced level athletes can try 10 push-ups every minute on the minute for 100 total reps if you prefer.

Cooldown:
30 push-ups, 30 squats, 300-meter run or one minute of jumping jacks
20 push-ups, 20 squats, 200-meter run or 40 seconds of jumping jacks
10 push-ups, 10 squats, 100-meter run or 20 seconds of jumping jacks
Light stretches throughout each set.