Why would anyone spend a long time climbing to fight a duel?
Simply take off meet up and fight.
It's called realism.
Here are a couple of action reports from WWII.
S/L "Tony" Gaze (Australian) of 64 Squadron recorded in his Combat Report for 11 October 1942:
15 miles inland from Dunkirk I noticed 4 F.W. 190's approaching the Wing at about 27,000' from the direction of St. Omer. I climbed up into the sun and led the Squadron down. Two of them immediately rolled over and dived away, the other two turned gently right, climbing. I easily out-climbed them and closed, the right hand E/A went straight ahead, whilst the left one turned left, I easily out-turned him and fired a long burst from the port quarter at about 300 yards hitting him on the starboard wing with H.E. (cannon) as the attack developed into a finer angle. Just as I got to astern I hit his slipstream but came back and fired a long burst closing from 300 yards to 50 yards dead astern seeing cannon strikes on the fuselage. I broke away to avoid a collision and immediately iced up. I think I must have hit the pilot for, after the first strike, the E/A took no evasive action whatever, merely going into a gentle dive in which I overtook him although I closed the throttle. Even when further strikes were seen he flew straight. The actual combat took place at 30,000'.
P/O D.G. Mercer of 122 Squadron recorded in his Combat Report 6 December 1942:
I was flying Yellow 1 on the port side of the Squadron, we had just left the French Coast at Calais at 23,000 ft., W/C ordered Squadron to turn to port, there being many enemy aircraft about. I had been watching several aircraft which I could not identify, about 5,000 ft. above and behind. During the orbit I lost sight of these aircraft and when next I saw them they were diving down from the left quarter from behind. I gave my section orders to break left. My No.2 (P/O T. Parker) turned after me, but not tightly enough, and I saw him go straight down with two 190’s after him – his aircraft didn’t appear then to be damaged in any way. I came round on my turn and attacked the second of the two 190’s from the port side at a point blank range of 50 yds., I gave a one-second mixed burst and saw the Hun’s tail unit break off in pieces. He immediately went into a spin and I last saw him at about 17,000 ft, still going down. After breaking off, four other F.W.’s had come down on me, but by evasive action and full out climbing to 30,000 ft I avoided them, during all this time six more F.W. 190’s were above me. I claim this F.W.190 as Probably Destroyed.
On 12 September 1942 Flying Officer Emanuel Galitzine, flying BS273[nb 4], successfully intercepted a Ju 86R piloted by Fw Horst Götz and commanded by Leutnant Erich Sommer[nb 5] above Southampton at 41,000 ft. The ensuing battle went up to 43,000 ft and was the highest air battle of the war.