My 8mo DTS are actually pretty good with napping during the day (one at 9ish, 12:30ish and 4ish) but sometimes it is a struggle to get them to sleep for the 'desired' length of time - i.e. more than 45 mins!!
Having read through some recent threads about toddler's nap times, I just wondered at what age does nap time stop being a battle of wills between baby and mum and become something that your LO actually asks for?