The Gunners moved back above north London rivals Tottenham with a 4-1 win over Wigan at the Emirates Stadium, which confirmed the FA Cup winners' relegation.
"We just have great experience in knowing what to do when the time is right. It is funny. It happens every year," said Walcott. "We tend to finish very strong. I think it is just because the players want it so much."
He added: "It (Champions League football) is big for the future of the club and the players. We have been in it for the last 15 years and we don't want to be the players who are not part of that.
"We just need to show that in the mid-season and at the start and we could hopefully be even higher than we are and not have this situation we are in. But it is very positive, and we will be fighting strong on Sunday."
With Olivier Giroud serving the last of his three-match suspension, German forward Lukas Podolski was deployed in a central striker role, scoring the opening goal on 11 minutes and Arsenal's third just after the hour.
Walcott has made no secret of his desire to the lead the attack as he had done to great effect earlier in the campaign.
"Wherever the manager wants to play me, I will do that for the team. You can't fault Lukas at all - he grabbed two goals up front and I got one as well," said Walcott, whose close range strike put Arsenal back in charge after Shaun Maloney's superb free-kick had briefly given the Latics hope of pulling off another great escape.
"So if things are going well, there is no need to change anything, I believe. I'm the sort of player that if things are going well, don't change them.
"I am making runs in and the manager is playing me up front now and then. I can wander at times and it works - there is a lot of rotation in that front line so when it is working, don't change it."
Source: PA
Source: PA