Do your children have similar temperaments?
DS1 was a pretty demanding baby and toddler, but around age 3.5 his temperament shifted a bit and he has become much more easygoing. 3.5-5 have been pretty great with him!
DS2 was a fairly chill baby (though he was a terrible sleeper) but has been a very challenging toddler. He's 2.5 and I wonder if he will remain more challenging!
DS3 - still pregnant so will be very curious to see how his personality is.