The key to success with creating flaky danish pastry is not pushing anything too fast.
Speaking about butter, using a good butter, sometimes labeled as "European butter" with less water and more fat helps create flakier pastries.
But using regular butter is just fine. Amish roll butter is a good choice .
If you don't have a whole lot of time to make the pastry from start to finish, you can break up the work and make it over a few days.
The pastry dough can be left in the fridge for a few days.
A word of wisdom from an amateur baker - Besides some good technique, which doesn’t require a skill so much as patient and time; choosing high end flour and butter is the different between mediocre or extraordinary pastries.
When it comes to baking pastries you definitely get what you pay for.