Yes, maybe if Arsenal only focused on the Premier League, Arsenal would have the opportunity to win the Premier League trophy because for several seasons they have always failed to become champions in the EPL. Indeed, if you look at the tight competition in the UCL season that has just ended, of course there be many strong clubs like Manchester City in the 2023 season. 2024 who failed to advance to the final. and Arsenal will certainly have the potential to face difficulties when competing in the UCL 2024-2025.
It's hard for all clubs to start, continue and finish a season with only one target to focus on. Because life is uncertain and a season is long enough with so many uncontrollable, unexpected factors that force clubs, coaches and players have to try to play as best as possible in most of their matches and have to adjust their targets, focuses with time.
So they usually start a season with multiple competitions and have to adjust their targets, narrow them down through a long season. Arsenal will have to face with and beat many strong teams in Premier League and Champions League. Their more realistic target to win a trophy in a new season is Premier League where they ended two latest seasons as a runner-up and can step up to a higher position for a champion next season.
Yes, you are right, it is not easy for every club to achieve their expected targets even though they only focus on one competition, like Tottenham last season where they only focused on the Premier League because they did not play in the Champions League, in fact they still had difficulty winning the Premier League title. Even though at the start of the season he seemed to consistently win, as did Arsenal, he still had to perform as well as possible in the Champions League because this is a prestigious competition even though his target was to win the Premier League title.
I believe Arsenal can go further in the Champions League and also try as hard as possible in the Premier League, the most important thing is that Mikel Arteta can always overcome existing mistakes without having to feel pressured because Manchester City will always remain their main competitor. I have seen in the last 2 seasons actually Manchester City is not much different from Arsenal, as long as this club remains focused, then they can break Man City's dominance.