My advice is don't have that expectation that you must get Akagi. Set a goal of "okay, I'll do it for like 20 minutes a day" with the expectation that you'll likely get nothing from it and continue on progressing the world map the rest of the time. I got Kaga after like 8 attempts but Akagi didn't come for like another month and a half.

If you don't mind on skipping out on some Destroyer/Cruiser blueprints you can clear 3-4 Hard Mode to Safe, that way you can just do the boss node for the chance at Akagi instead of having to do 3 extra fights. You are also getting carrier blueprints for Saratoga.

Also try to combine it with some other long-term goal like farming experience for PR so you know you are at least making progress in some way even if you aren't actually getting any new ships.