Are you...trying to conflate shitty memes by people who have no idea to dunk on actual published Military documents on how to avoid protracted sieges?
The Leningrad example is crazy, because that is what they absolutely should have done. Instead Army Group North got completely nerfed by mid July/August and Ritter Von Leeb specifically requested OKH (Von Brauchtisch) 13 times(!) over 25 days for an additional 13 divisions, which is what he stated would be the required strength in total to take Leningrad without a siege.
Given that the exact timeframe, was when the Loetzen decision was happening and additional units from Von Bock's Army Group Centre got diverted to Rundstedt, Army Group North was further overstretched and lacking in manpower, divisions and overall strength. Eventually by late August, OKH gave Leeb 4 of the 13 divisions he requested, leaving him 9 short.
What happened then was Army Group North comprised of Kuchler's XVIII Armee which was severely undermanned with only 5 infantry divisions, the 4th PanzerGruppe which had been campaigning hard for 3 months and in desperate need for resupply and rearmament, and XVI Armee which was stretched along a 600km frontline that needed manning.
The Germans simply did not allocate enough manpower to actually take Leningrad by storm, which is what they undoubtedly should have done.
On to Fallujah:
The 1st Marine Division and the 5th Marine Division did not have the shortages of power that the Germans had.
They spent 1 week setting up checkpoints around the city preventing anybody from leaving. Mistake number 1: It forced all the insurgents to dig the feck in as they were surrounded anyway.
They then spent another week, trying to precision bomb dug in troops in a city. It wasn't very fruitful as the insurgents just hid underground or in civilian housing or in rubble.
After a huge delay, the Marine Combat teams began to clear out the city house by house piece by piece, area by area. Slow, painful and high in casualties.
All documented retrospectives indicate this was the wrong move.
Baghdad:
3rd Infantry Division took Baghdad international airport and rather than spend a week fortifying their position and trying to create a siege situation, they ran two armoured columns straight through the middle of Baghdad in 2 seperate days.
This caused absolute chaos and completely sliced command and control of the Iraqi forces.
Right After the 1st Marine Division cut through from the North forming isolated pockets of weak resistance.
Once the main administrative and command facilities fell the pockets of insurgents could be mopped up as they would have nowhere to hide or retreat to as they were in very small pockets trapped.
Now please, if you have something useful to contribute on this matter, please do but that shitty meme certainly wasn't it. all of the above were concluded by US military analysts conducting retrospectives, so it's not just me claiming this.
EDIT - Just saw the 2nd meme:
I refer to Field Marshall Von Kleist's comment around taking Stalingrad as referenced in Alan Clarke's Barbarossa, Chapter 11:
For the Don crossings were virtually undefended. Timoshenko’s troops had been hustled out of one position after another in the course of their retreat, and those who had not been trapped west of Rostov had already left the Don behind and were filtering up the valley of the Manych or making their way due east into the Kalmyk steppe, where the broken-up country and balkas of the Yergeni Hills would afford them some cover.
Kleist, who was particularly free with comment on how operations in other theatres should have been conducted, claimed after the war, “The 4th Panzer Army . . . could have taken Stalingrad without a fight at the end of July, but was diverted to help me in crossing the Don. I did not need its aid, and it simply got in the way and congested the roads that I was using.” A sergeant with the 14th Panzer Division has described how We got to the Don to find most of the bridges down, but very little sign of the enemy.
Now, German Field Marshall memoirs are always a fecking sketchy source, but Alan Clarke and David Glantz most summarily agreed with this assessment. The 4th Panzer Army at that point had 1 Russian Rifle division blocking it from Stalingrad but they were rerouted to help drive to the Caucasus.