Bear in mind casualties happen a number of ticks per day in EU4, what I expect is something like this.
Lowest speed - ticks 1/10 of a day - matches combat damage ticks
Next speed - Ticks 2/10 a day or 5/10 of a day - more like euiv on speed 1 ish
next speed - ticks daily and has combat tick at the same as euiv
next speed - same as speed 3 for eu
next speed same as speed 4 for eu or speed 5
Generally you'd use the two highest for peace time, and the two lowest for combat in Singleplayer, and in multiplayer youd play at speed 2 or 3 most of the time, and speed one for major wars.
Would you play 300-500 hours to finish a campaign. That's what eu4 speed would mean.