I know how long is a piece of string...
I don't have a problem with my letdown at the beginning of a feed. However, some days I notice that that I get more letdowns through the feed than others (characterised by sensation &/or feeding pace). Some feeds I only notice the one at the beginning. DD is a slow feeder at the moment (typically up to an hour at a time - 10wks old) & I wondered whether I am getting 'enough' letdowns or whether I am slowing her down IYSWIM.