How much time do your 2-3yr olds spend at pre-school/nursery?

Morning all? 

Just wondering really. Particularly in those who spend quite a bit of time there each week - how did it effect their behaviour, mood and progress? Also interested in those whose children were shy, nervous or clingy and how much they go and whether it has helped improve confidence. 

My little one has struggled and is v anxious. She is getting into it now and we are increasing to full day and half a week (she's three) - this is more than I originally planned but feel she poss needs it, maybe more. They have mentioned me increasing her time there and obv they are entitled to 15 funded hours at this age. I don't want her to feel like I've abandoned her though! She's v sensitive. However, it might actually be just what she needs, not sure! 

Do your three year olds do half or full days? Half at her pre-school is 9-12 and full 9-3pm.