This is an efficient way of boosting CQC achievements for 50 and 250 wins and reach Professional and Level 50 (268,765 xp) by playing Capture the Flag. Playing any game type legitimately is very frustrating because the small player base means more time is spent searching for a game than playing. Very few legitimate CTF games take place so finding your boosting squad is reliable. It took 60 hours (20 x 3 hour sessions) of boosting to reach 247 wins and 200,000 xp. The in-game timer seems to wildly overestimate the play time recording 120h.
My final stats when I reached Rank 50 are shown in the screen shot below.
It's suitable for 6-8 players, optimally 8 players because you will have a full lobby and prevent interference from random players. The attached spreadsheet is visual representation of the roles the teams and players.
If you have 4-5 players you can take turns to win Deathmatch, this is not as efficient as Capture the Flag method.
Alternatively you can also try to set up a Team Death match game with random players. Whilst a TDM game is longer than CTF, that's offset by the fact that everyone on the team gets a win (its possible to win consistently as you will likely outnumber the randoms which are usually low level. You will be communicating and coordinating play in a party and very likely have access to better equipment). I recommend you don't inflict overwhelming defeats on the randoms as they will leave quickly. Its in your interest to make the games close and keep the lobby full.
Every one in the team has potential to earn more than the 85 xp players get when they are on the team that dies. For a win you can expect a total of 3000 - 4000 xp across the team. Plus its fun to be able to play the game properly rather than repetitive boosting and your skill level will improve.
For CTF boosting I recommend everyone use Condors as they are speedy for capturing the flag (all pips in engines and use speed boost) and weak to make killing faster (all pips in engines and weapons, switch off shields). You can optimise load outs for either speed or offense dependent on your role and unlocks. Each team should form a squad of 4 players and designate one player from each team to keep tabs on the other players role and call out each players role at the beginning of the round. Once the squads are ready they should beginning searching at the same time. (Because of the environmental complexity of the Ice Field map I recommend skipping it). The teams should alternate between dying and capping the flag. The team capping the flag should have one player who captures the flag twice in the round. The other player caps the flag once and the remaining player(s) should congregate at an agreed spot in the centre of the map to kill the other team. The player(s) getting kills should repeatedly kill all the opposing team. Once a player has been killed and respawned they should return the centre of the map to be killed again. To maximise the number of kills the player dying should switch all their pips to engines and weapons. The player killing should switch pips to weapons.
The player getting two caps should boost and quickly capture the first flag and deliver it (there are on screen indicators for capturing and delivering the flag which are in fixed positions on the map). The player who is capturing the flag once during the round should wait by the flag spawn gate to collect the second flag once it respawns. When the first flag has been delivered it will respawn at the flag spawn gate, there is a 2 second cool down before it can be picked up. The player who has just delivered the first flag should go back to the flag spawn gate ready to collect the third flag, once the second has been delivered. Once the third flag has been delivered the game will end you will be returned to lobby and the teams will swap roles in the next match.
Once every one becomes familiar with their roles the match times will decrease and you can obtain 15 - 20 wins in 3 hours.
In you only have 6 -7 players then random players may join the game. If this occurs and the random player collects the opposing teams flag, then the team capping the flag will not be able to deliver. You should kill the random player and recover the flag in order to carry on. You can try to block the random players on your friend lists for future games, I am not sure how effective this is.
Sometimes a player will not load into the game and be stuck at the loading screen. It is recommended to be patient and stay in the match. Once it's over they will load back in the lobby and be able to carry on with the next round. They will be awarded the win or xp appropriately.
Sometimes a player will load into a game, but will be invisible to the rest of the players in the game. If this happens the invisible player should quit the match and exit the game. Resetting the game should fix the problem, if not restart the xbox.