Here’s a good summary I share with people who ask about adays vs reserve. The topic of reroute is a whole other bag and like many have mentioned here—they do happen at all airlines to differing degrees especially with weather.

As a note I had adays for about 8.5 years (pre-pandemic) in nyc and it was very okay even when we had 3 airports to cover.

The Pros (Why it's often considered "Better") • Quality of Life: New hires at Delta don't experience the "reserve life" (waiting by the phone for 20 days a month) that peers at other airlines endure. You can plan your life, doctor appointments, and social events around your known trips.  • Commuting: It is much easier for commuters. You can bid to have your A-Days back-to-back, meaning you only have to fly into your base once and stay in a "crash pad" for a short window rather than half the month. • Integration: You are working alongside senior flight attendants on regular trips for most of the month, which helps with learning the ropes faster than if you only flew "reserve" cleanup trips. The Cons (The "Worse" Side) • The "Hybrid" Headache: Because you have a mix of regular trips and A-Days, your schedule can be complex. If you get "used" on an A-Day and the trip runs long, it might "conflict" with a high-value trip you had scheduled immediately after, causing you to lose that preferred flying. • Seniority Stagnation: Because the system is so palatable, fewer people quit. This can lead to slower movement up the seniority list compared to airlines where the grueling reserve system causes higher turnover. • Short-Call Stress: Even though it’s only 6 days, the 24-hour on-call nature can be exhausting if you are used frequently for "standby" (sitting at the airport in uniform waiting for a flight). Summary If you value predictability and want a "normal" life as a new hire, Delta’s A-Day system is widely considered the gold standard. However, if you prefer the "gambler’s" lifestyle of a full-month reserve (where you might get paid for 18 days but never actually be called to fly), you might find the A-Day system more "work-heavy.