How do you cope:
people are usually more efficient when they do a job they've practised before
you know the ropes re HV, doctors' appointments, how equipment works, probably have all relevant phone numbers by heart- so very little time is spent accessing new information
with experience it gets easier to distinguish between jobs-that-absolutely-have-to-be-done-this-minute and jobs that don't
having an older child who has to get to nursery or school or the doctor is wonderful for focusing your mind on which jobs are immediately necessary
with their second child you've often got better access to support groups, you've made friends with other mums who are in the same situation at approximately the same time
with the second, you tend to be less nervous- so also a little more ruthless (yes, I can hear that baby's grizzling but just at the moment he's safe in his cot so I'm dealing with big brother on the potty)
at times, having two can actually save you time, with one sibling keeping the other occupied and amused
(have a lovely photo of dd- 4 at the time and a very anxious child- curled up next to her sleeping brother, evidently seeking comfort in his reassuring presence)
Does all this mean you have to opt for that extra (if more efficient) work?
Of course not. "This is the right level of work for me" is perfectly fine.