Japanese had 21-22 years to study submarine warfare of WW I and over two years to study the Battle of the Atlantic. Yes they had ordered some escorts but in sort of prototype quantities (plans could sit on the self until needed?). One or more were overly complicated. Japanese DDs and escorts were woefully short of sensors and even numbers of depth charges. for an Island nation that relied on imports of many things this was a major failing. Japanese escort commanders were considered 2nd rate. Not by their enemies here (although that too) but escort duty was sometimes seen as a demotion or dead end command. Some commanders had not gone to the Naval Academy but to the merchant marine academy. If there was a caste system in the RN against the "wavy navy" one can only imagine the regard that regular Japanese naval officers held the escort commanders in.
The US had the same opportunity to study the Battle of the Atlantic as the Japanese had and they did even worse. They even had the advantage of private tutoring from the British and they still failed spectacularly. At least the Japanese built some escorts pre war whereas the USN did not get their first destroyer escort into the service until after the wolf packs had been defeated.
The Japanese get unfairly castigated for their ASW efforts but the reality not that not just the US but the British as well failed to devote enough resources to ASW until it was almost too late. It wasn't until the Casablanca conference in January 1943 that the Allies finally realized that if they didn't secure their supply line in the North Atlantic their invasion of Europe would not occur. The RN Home Fleet released some 20 modern destroyers to form 3 Support Groups which were pivotal in the decisive convoy battles of May. Also Coastal Command also received more Liberators.
As a comparison I have plotted Japanese and Allied Merchant Vessel losses in 1942 and the difference is staggering. Yes the Allied fleet was much larger but it wasn't 10 times as big. If you look at the cumulative losses suffered by the Allies up to May 1943 their merchant fleet was well under water (pun intended)
You don't introduce convoys until you until your enemy forces you to. Convoying is very inefficient, the slowest ship determines the convoy's pace and much time is wasted in port.
The Japanese losses in 1942 were sustainable; in fact, their merchant fleet was much the same size at the end of 1942 as it was at the beginning. On the other hand the allied fleet didn't exceed its prewar levels until some time in 1944 and their demands for shipping had grown much more.
Japanese losses did increase in 1943 but the problem doesn't become critical until the last quarter. At this point the Japanese do react by constructing escorts and introducing more convoys.
Actually increasing their ASW effort was a bit in vain anyway as they have a real problem with inferior technology. The problem for the Japanese in 1944 wasn't just wasn't lack of effort it was lack of technology.
For an in-depth analysis I have attached of copy of the USSBS study of The War Against Japanese Transportation 1941-1945 for your reading pleasure