As travel demand on the line has been growing since its launch in July 2017, BKK has decided to introduce yet another service development: middle of July 2019, service frequency is 10 minutes every day of the week.
Passengers are advised to buy their tickets in advance to avoid queues and so that buses can maintain their schedule and depart on time. The ticket for the 100E has been available as a mobile ticket via a mobile app since June of this year. Tickets can be purchased from TVMs and at BKK customer service centres as well.
https://dailynewshungary.com/overcrowded-airport-buses-cause-daily-problems-to-tourists-in-budapest/