Perch was a short hard stab, beaten back by a short hard stab and the feeling it could get very bloody. Monty's caution meant not too many men were burned in the operation, and significant forces were drawn into the ongoing fight that essentially depleted the German mobile reserve so there was very little indeed to face Patton's breakout to Brittany.
Intentional or not, Monty's conduct at Normandy was professional and effective, if a little slower than the US commanders who were less concerned about casualties. The British forces (including Monty) had learned in France (1940) and in the North African campaigns about the dynamic mobility of the German forces, and their ability to cut off and destroy advancing units who hadn't minded their flanks.
Kasserine Pass was a textbook example of professionals making mincemeat of amateurs. Relatively small Wehrmacht forces on dubious supply lines feinted a retreat into prepared positions where the Yanks were shot up like fish in barrels, something the British hadn't fallen for in years. To their credit the US Army took the defeat on the chin, sacked a lot of dead wood and brought their infantry tactics especially up to scratch.
Given the relative experiences of the UK and US in WWI and early WWII their commanders reacted to type. The British had suffered the loss of most of their materiel and nearly 300,000 men at Dunkirk: the threat of another loss of that scale made wholesale commitment of armies to perilous adventures anathema to them, and the application of materiel superiority was the clear path to victory: it worked in WWI where pouring out blood had not.
Despite an even greater superiority in materiel, the US found themselves in a two front war where the public felt more strongly about the pacific theatre. Courageously choosing Germany First as a policy Roosevelt sought to bring the war to a swift conclusion leaving no stone unturned in the quest for total victory: Army, Navy, the new Air Forces and secret weapons all got massive funding. A small "hard" army (about 80 divisions: US manpower could support a far larger force, albeit to the cost of industry) armed, equipped and supplied to an amazing standard was chosen as the preferred tool (perhaps with memories of WWI caricatures of amateurish US soldiers in mind). In the event the US pride and insistence they were on par with the British and even the Germans was dented at Kasserine but they took the necessary steps (unit comms especially, they needed more radios and the doctrine to use them, but also pretty simple matters of discipline) and made their forces respected by the end of the war.
Patton crystallised all the positive aspects of the US leadership: bold competitive and prepared to spend blood to take blood. Some parody him as a self publicist but he's really typical of hard-cursing big-talking competitive US generals of the day: MacArthur was the real self serving maverick
commander.
Monty in many was a typical UK commander in his military conduct: effective campaigns exploiting materiel advantage and moving cautiously to save blood. However his rank egotism was disgusting to his fellows and allies alike. There are rumours he was gay: either mud to smear his name or another reason for contemporaries to dislike him.
Eisenhower was the exception to all the sterotypes, perhaps a staff rather than a field commander he had the communication and negotiation skills to get the US Navy, US Army, Royal Navy, British Army and their various air services to cooperate, and to pick and stick to plans that would work: a freaking miracle, and on only matched on the Axis side by Kesselring (an acknowledged genius). Ike wasn't the first general to make President, but he was probably the first general to deserve it.