If you're seriously interested in the question, I'd recommend looking at original academic research. Examples (none available full-text free) of the sorts of things that look helpful are below. I pulled all these off the first 50 items that popped up when I searched on the words "parental time allocation child outcomes" in JSTOR. Unfortunately none are available free full text (but they'd be readily available in a university library if you're near one); I've tried (when possible) to provide short snippets from the abstract that give a sense of what appear to be the full findings, but I haven't myself read the full articles so am not really in a position to say.
(The very, very quick summary of what I know about the findings in this area, other than that "it all depends," is that for children of parents with less formal education, high-quality childcare, early (and often!), produces better outcomes, as measured by things like academic achievement -- staying in school, passing grades, doing well on tests that measure cognition, than does providing childcare (just) by the parents/extended family. Low quality childcare does not. For highly educated parents, it doesn't seem to matter much -- good quality childcare is good, and so is parental care (and of course low quality childcare is not good). I'm not really informed on research about parental time allocation once kids are older than 5 or 6 and its effects on academic or other achievements, so can't even try to summarize that).
Parent's Time with Children: Does Time Matter for Children's Cognitive Achievement?
Amy Hsin
Social Indicators Research
Vol. 93, No. 1, Time Use and Qualities of Life (Aug., 2009), pp. 123-126
Published by: Springer
Article Stable URL:
http://www.jstor.org/stable/27734904 ("...the literature points to key disparities in the quantity and type of parent child interactions -- the verbal interactions and the type of activities performed together, for example -- that suggest that children are socialized in ways that reinforce existing inequalities... . These studies suggest that there may be important differences in
how time is used and that these differences may contribute to socioeconomic disparities in child outcomes. In spite of these studies, research that has sought to establish an empirical link between time with children and child outcomes is relatively limited..." (emphasis in original))
Maternal Employment, Nonparental Care, Mother-Child Interactions, and Child Outcomes During Preschool Years
Kei M. Nomaguchi
Journal of Marriage and Family
Vol. 68, No. 5 (Dec., 2006), pp. 1341-1369
Published by: National Council on Family Relations
Article Stable URL:
http://www.jstor.org/stable/4122863(""... maternal employment during the previous year, especially full-time employment, was related to care by nonrelatives, longer hours in school settings, fewer positive mother-child interactions, and less reading with parents at ages 2 and 4. Controlling for these mediators, maternal employement was related to children's lower hyperactivity, more proscocial behavior, and less anxiety at age 4, although little relationship was found at age 2. The results indicate that preschoolers may beneft from maternal employment, but benefits may be offset by long hours of nonparental care and fewer positive mother-child interactions.")
Child Care, Women's Employment, and Child Outcomes
Jane Waldfogel
Journal of Population Economics
Vol. 15, No. 3 (Aug., 2002), pp. 527-548
Published by: Springer
Article Stable URL:
http://www.jstor.org/stable/20007828(Looks informative, but no useful summary pointing either direction in the abstract)
Mothers' Time with Infant and Time in Employment as Predictors of Mother-Child Relationships and Children's Early Development
Aletha C. Huston and Stacey Rosenkrantz Aronson
Child Development
Vol. 76, No. 2 (Mar. - Apr., 2005), pp. 467-482
Published by: Wiley
Article Stable URL:
http://www.jstor.org/stable/3696515("...With family and maternal characteristics controlled, time with infants predicted high Home Observation for Measurement of the Environment (HOME) scores and maternal sensitivity, but bore little relation to children's engagement with mothers, secure attachment, social behavior, or cognitive performance from 15 to 36 months. Mothers who spent more time at work had higher HOME scores. Maternal time with infants may reflect maternal characteristics that affect both time allocation and maternal behavior."