A few comments I would like to make.
Average bombing alts for the 8th AF over Occupied Europe was at least 20,000 feet. Raids were done between 20k and 29k. There were several reasons for this; The first of which is that the B-24s best alt is 25k and the B-17s is 29k. Both bombers could fly faster the higher they flew from S.L. to 25,000 feet. Secondly was the Flak. Flying below 20k was not done because of the heavy AAA defenses, not even at night. Lastly the escort fighters operated at best at alts above 20k, especially the P-47 series.
Escort to bomber ratio. Well, this varies a lot depending on the year. The 8th AF flew from 1942-45 and peaked @ mid 1944 as far as total combat power. In June of 1944 it could muster @ 2000 heavy bombers and @ 950 fighters. Thats operational and crewed a/c that could actually roll on a mission. Many times missions were flown with as many escorts as fighters, but the ratio depended on the exact raid. It could easily fly 3 x 300 bomber raids and have them all escorted with an equal # of fighters at that point of the war. To put it in FSO perspective, for every 12 formations of B-17s or B-24s, you could have anywhere from 18-36 escorting fighters.
LW fighter tactics tended to be to attack bomber groups and formations that had suffered losses already just like you tend to see in FSO. Stragglers and bomber flights that were damaged or missing a plane were singled out. Reasons are obvious enough to anybody that has tried a run on a tight bomber group.
"1000 plane raids". Were not the rule. They tended to "up" that #, but usually bombed several different targets. Again, it was specific to the mission. Anywhere from 100-800 heavies, escorted by fighters could be expected to raid any specific target on any given operational day, with the total # of a/c upped anywhere from several hundred to several thousand.
Added to that from June 1944-May 1945 is the two ETO Tactical Air Forces (RAF and USAAF) which could muster @ 800 bombers and @ 2000 fighters combined that flew medium bombers and fighter-bombers. They could easily escort any bomber group with many fighters if they chose to do it.
RAF Bomber Command had 1100 heavy bombers that usually operated at night (Lancs, Halifaxes and Mosquitos) for those interested in the #s there. Same thing, some raids were all on one target, often they attacked several different targets.
The notion that somehow bombers flying high or without a decent escort is somehow wrong or innacurate just isnt the case. Also the logs dont show the LW doing poorly in setups like these despite some claims to the contrary: "Mighty Eighth", "Der Kanalkampf", "Point Blank Range", "High Blue Battle", and this one "Should Have Been a Milk Run"...the LW has scored more kills, not less, and thats just a few I looked at featuring Allied heavies vs the LW in the ETO. Plane performance issues or no, they seem to make out ok.