The timeline for Heroes of Olympus is beyond crazy.
It starts in mid-late December and only 4 days away from the winter solstice. Jason, Piper, and Leo have to get from CHB all the way to San Francisco in only 4 days while also dealing with monster attacks and stopping for help in Quebec.
It took Percy, Annabeth, and Grover two weeks to get from CHB to Los Angeles in the first series and the main antagonist of that series wanted them to get there quicker.
The trio somehow managed to get there and free Hera on time and then there is a six month pause as nothing happens.
Yes, Leo and co. needed to build the ship but there isnt much of a reason why Percy couldn't be doing his thing with the Romans while the ship was being built.
Speaking of the Romans, Son of Neptune takes place over 4.5-5 days. Its the 20th when the SoN trio set out to Hubbard Glaciar to free Thanatos from Alyconeus and they need to do that before the 24th.
From San Francisco to Hubbard Glaciar is a 15-17 hour trip. Just getting to and from Camp Jupiter would have taken 2 of their 4 days.
The group also had to stop and try and get help from the Amazon's, got held up by Phineas and the Harpies, literally slept at Franks Grandma's house, and took shelter with Iris from the approaching army of monsters.
They actually do miss the deadline for freeing Thanatos since they defeat Alyconeus on the 24th and have to use Arion to get back to camp but it doesnt do anything since Octavian doesnt become praetor like the threat has set up.
From there all through Mark of Athena and until the ending of Blood of Olympus is one month and 7 days.
Somehow the seven managed to get from San Francisco to Kansas, have a chat and friend in a random field, fly from Kansas to Georgia, play a puzzle game and get ambushed by Octavian and co, flee the US entirely before stopping at the straight of Gibraltar to talk with Hercules, do a side quest for Hercules, sail to Rome and both free Nico from a jar and find the Athena Parthenos, sail around the Mediterranean from Libya to Malta to Epirus, defeat Cricus or whatever that giants name was, sail to Ithaca and all around the islands of Greece, and have a major battle in Athena where Gaia rises from her sleep.
Most of this isnt including the stops to fight monsters, meet with gods, or having a drawn out side quest.
All of that happens in one month and seven days.
No wonder Heroes of Olympus is a mess if the majority of the stuff that happens in the series takes place in little over a month.
I didnt even mention most of what happened with the "war" between Greeks vs. Romans.
Compared to the series before and after Heroes of Olympus, Rick probably should have done another draft before actually publishing it.
The first series took over 4 years in universe to complete and while the third series takes about the same amount of time (December to August again) notably the story doesnt leave the US and has a lot less going on.
Only one group of villians (the triumvirate) to deal with and a lot less travel time, side plots, and the monster attacks were mostly kept to a minimum.
