Here’s my real world experience. Every year there is a big 5k in my neighborhood. I wasn’t a runner but one year I decided to run it. Not knowing anything about running, my strategy was to do 2 or 3 runs a week for a weekly total of 6-9 miles and each of those runs I’d do them as hard as I could. Every run was an attempt to go faster than my previous run.
Yes if you don't train, easy running is better than that. It doesn't make it good training. Compare the 5k times of a guy who runs 50mpw easy and the one who does 50mpw with 1 workout/week were they run at say 10k pace. The second guy is likely to be 30s-60s faster.
Seriously we did this every year in XC. We would easy run over the summer and come back and run 18 min 5ks. 3 weeks later basically nothing other than the same mileage with 2 races/week(yes we were overraced😁) we were running 16 high on the same course.
Yikes, at 2 races per week, you can only do easy days in-between. Good on your coach for not doing workouts over summer, you'd be burned out by the end of the season. Your races were your workouts.
2 xc races a week was the standard in the 90s. I ran 5 races in 14 days two separate times my senior year and never went more than 10 days without racing from mid August to November. I didn't finish the season well but others did just fine on similar schedules.