Continued gameplay after beating Contra

I have beaten Contra during my childhood 2 times in a row, and i have noticed a little change. If you take a look at Gaming Forums, you will see reports that the game gets harder after beating.

LukeInside user reported after beating the 3rd time:

On the third round the amount of troopers is increased and their running/shooting speed is faster so watch out. I wonder how far can a player get before the game becomes unforgiving :) I'm on Snow level now and on third walkthrough. What are your experiences with that classic game?

User Damon Plus, reported that after the 5th time, things slow down a little on difficulty progression, but you will still see some hard to kill mobs:

I got 7 games straight through the game, and I finally died at the mid-boss of the 8th level. After about the 5th time, difficulty doesn't increase anymore, but if you die, you're screwed. Every boss takes forever to kill. I died because the flying yellow things he trows absorbed a lot more bullets that I could shoot before they overwhelmed me.

What we can get after reading this reports is that:

• Bosses will need more damage to be killed;
• Enemies that require more than 1 shot to kill, will need more damage to be killed;
• Amount of enemies(specially troopers) will increase;
• Shots will be faster;
• Spawn points for troopers will be less predictable;
• Max points is 6553500 and you will get at the 8th run(jonebone post);

Take a look at the following video: Contra After Beating the Game 100 (One Hundred) Times in a Row - Link is broken and i could not find any other streaming service with it uploaded, unfortunately.

You can see at this link what happens at the 8th loop of Nes Contra. Besides the quality of the video(7 years old) look at how much the difficulty increases. And at the 12th loop in the last stage, you can't kill the "flying scorpions(Bugger)" just by spamming shots while running through the stage.