I know a woman who had twins and got pregnant within 6 weeks so had 3 under 1! huge amount of respect for her! she had to give up work though and the family moved in with her mum and also got some childcare help. they are 3&4 now and she said while at times it's great she does feel she didn't get to enjoy the baby stage enough and maybe missed out on it through the blur.
I have 2 yrs 7 months between my two and will have exactly the same again come January please god. worked out well, DS was independent enough, was able to take him out of the car and know he wouldn't run off while i was getting DD out so that kind of thing helped, he wasold enough to understand to be gentle etc and they are best buds now. DD worships DS and he is very good to her.