There's no harm in leaving a male with a female for too long, or introducing him too often. But if you put them together too briefly, or at the wrong time, you risk missing your window and getting an infertile or low-fertility clutch.
The problem is that "the right time" can vary from female to female, or even year-to-year in the SAME female. I have better luck introducing males several times over a period of several weeks, starting just after brumation, and continuing through the first three shed cycles, or until the female is obviously gravid.

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Brad Chambers
WWW.HCU-TX.ORG
Breeder of:
Green Tree Pythons
Jungle Carpet Pythons
Pastel, Pinstripe, FIRE, Piebald, Clown, Lavender Albino, Leucistic, and Spider Ball Pythons
Striped Colombian Boa Constrictors
Kenyan, Rufescens, and Conicus Sand Boas
Red Phase Western Hognose Snakes
Spider Western Hognose Snakes
Albino Western Hognose Snakes
Locality Trans-Pecos Mexican Hognose Snakes
Southern Hognose Snakes
Eastern Hognose Snakes
Tricolor Hognose Snakes
Hypo Checkered Garter Snakes
Eastern Blackneck Garter Snakes
Stillwater Hypo Bullsnakes
Patternless Bullsnakes
S. GA Eastern Kingsnakes
Locality Desert Kingsnakes
Albino Desert Kingsnakes
Hypo Desert Kingsnakes
Mexican Black Kingsnakes
Desert Phase, Striped Desert, Newport, and Coastal California Kingsnakes
Locality Mexican Milksnakes
Spotted Mexican Milksnakes
Tangerine Mexican Milksnakes
Locality Alterna
Abbott Okeetee Cornsnakes
Mexican Baird's Ratsnakes
Cape Housesnakes
Tangerine Albino African Fat -Tailed Geckos
Locality Spotted Turtles