It’s hard to pinpoint this exactly as there’s no hard and fast rule but generally hungry babies tend to cry for a feed more often and will feed longer when you do offer them their milk.
At around 6 weeks of age, many babies also go through a growth spurt which can mean a hungrier baby for up to a week so the feeding routine you had may have just gone out the window! It’s worth bearing in mind that that this may occur so you can just increase the frequency or amount of the feed and then allow the pattern to settle back after a few days.