Depends on amount of weeds with seeds on them. Bagging helps reduce weed spreading. Thatch can also get too thick so yep, depends on how often you mow and whether you want to de-thatch at least once a year when aeriating the soil for better water absorption and to allow fertilizers/pesticides to seep into the soil more efficiently.

I do all of the above. Bagging only when there is significant rains to create more than average grass growth. Aeriating the yard with really dorky looking metal sole 3" long spiked shoe adapters - work like a charm. Balancing all the factors and yard looks great.