Be aware that each year the federal agencies state what they want funded (just like the kiddies state what they want for Christmas).
Congress only to give it, cut it or deny it (just like mommy and daddy).
Congress then adds stuff for their districts and state, and pork. The representatives and senators could be told to have their requests in by June 1.
There’s really no good reason why a budget can’t be produced in plenty of time.
Oversimplification to the level of disingenuousness.