Both my kids always napped since they were born.
My son is now 5, and is napping now.
My daughter is 8 and will nap, when very tired.
When they were younger and until about 3-4 years old... I planned things according to their naps.
IF a nap was sacrificed due to whatever events... then my kids get VERY cantankerous and moody and fussy.
THEN they are total grumpy monsters by evening.
HENCE, I do not, sacrifice naps and always work around it. Even on weekends.
My kids, are also NOT 'portable' nappers. Meaning, they will NOT nap anywhere, except at home in their bed/crib. They will not nap, on the go or in a stroller or in a car or at someone else's home.... no matter how tired they are. Hence, we always come home, for their nap time.
And, this has always worked for us.
My Husband, is GLAD that I kept to a nap routine for our kids and am 'anal' about it. (and he actually TOLD me, he is glad I was routine about our kids naps)... Because, he KNOWS darn well, how cantankerous they get, when they are over-tired.
AND it is NOT FUN... to be out, with 2 fussy over-tired kids. They don't enjoy it and we don't either.
I have ALWAYS... kept to my kids nap routines/timing.
Always.