You don`t get marks from too much agitatioin. They are from too little and certain areas do not get equal replenishment. Notice they are too light, not too dark.
That said, ID11 or D76 makes a really grainy neg. I was very disappointed with the latest version some 10 years old now. It worked well before. The two best developers are DDX and Xtol and they are way better than ID11 for D400. ID11 works fine with Delta 100 speed. Delta 400 in DDX is a beautiful combination.
The ultimate test is for agitation is a two reel tank with film on the bottom reel only and empty spacer reel on top. Use only one reel worth of developer, probably 8 oz. Agitate by inversion. This is the same as sheet film in holders where film is removed and replaced in developer twice per minute.
No agitation is more vigorous than this, but the key is it is random and complete. Your film will never mark.
You also do not want to pour film developer down the cap as it washes in one direction over the sprocket holes creating marks on the outer wraps. The initial immersion is most important as the wet edge needs to start and progress across the film rapidly without stopping or retreating. Dropping the reels into the developer accomplishes this. So does the Patterson Super System 4 tank which overcomes all the user controlled agitation problems.