Daily carbohydrate needs are not one number. They scale with how much and how hard you train, and getting this wrong is one of the most common reasons sessions feel flat.
Mainstream sports nutrition guidelines give ranges per kilogram of body mass per day:
Light training or skill work: roughly 3-5 g/kg
Moderate programme, around an hour a day: roughly 5-7 g/kg
High volume, 1-3 hours a day of moderate to hard work: roughly 6-10 g/kg
Very high volume, 4-5 hours or more a day: roughly 8-12 g/kg
The idea is to match intake to the day, so a rest day and a long-run day should not look the same on the plate.
A worked example: a 65 kg runner doing about an hour a day of mixed training sits around 5-7 g/kg, so roughly 325-455 g of carbohydrate a day. On a 2.5-hour long-run day that might climb towards 8 g/kg, around 520 g.
That sounds like a lot, but spread across three meals, a recovery snack and some fuel during the long run, it adds up faster than people expect.