i am super strict (and her dad says mean
) about Monster's sleep routine. MY sanity and the cleanliness of the house depends on it, so from day one I have been very punctual with her sleep. thusly, she is very good about it. however, we do adjust slightly..she used to go to bed promptly at 7pm, then I noticed she was not as sleepy at 7, so we switched to 7:30 (and adjusted the whole routine by 30 min) and it was perfect. SO I am strict, but understand that she changes daily, so the schedule should accomodate her changing.
That said..toddlers have a lot of "stuff" they go through..teething (mean molars, yuck) being a main one, which can disrupt sleep. If you think that may be an issue, a small dose of tylenol or advil before bed does wonders.
Also, the seperation anxiety thing plays a major part in toddlers too, and going into their room to cuddle and soothe them only makes it worse. not that you should ignore a cry, of course, but I would give it a moment or two to see if it calms on its own, or a quick peek in to make sure baby is ok, and then letting him put himself back to sleep.
I have found that the moms I talk to who have baby sleeping problems, pretty much universally go into baby's room to hold them and talk to them when they cry. monster rarely wakes up, but when she does I peek to make sure she is alright and let her calm herself down. its usually about 2 min of fussing then boom, her little butt is snoozing again.