Never heard of sitterving before but I can truly vouch for it being amazing for kid's learning. When my niece and nephew were here with me, I would often take them out to the park and watch them do their own thing while I am stretching in a corner. Many a times I saw both my niece and nephew trying hanging and ape swings on their own. My niece would never do it when I'd show her and ask her to do it. But when she gets space, she tries things at her own pace.