I would like to petition that Day Trader's difficulty be reduced by removing the "enemy cannot score a single point" requirement.
I play primarily solo (and usually for short bursts of time) and doing PUGs in The Index I find most teams leave after one or two rotations. In order to prevent the enemy from scoring, especially in round 3, I have only found success while playing as a duration Limbo. In this setting I find it equally necessary and boring to play Limbo and camp the objective. For me the price of failure is the time investment and the single point margin for error is razor thin and I find it frustrating that I often have to choose attempting the last wave with bots or having leave a wave early.
The Goldilocks setup would be to PUG to the third wave with a team that stays and understands the mechanics of stacking investments before turn in (I turn in if the clock is low otherwise wait until +8), and then I rely on my team to score while I shoulder the responsibility/blame for any scenario that results in a single enemy point being scored.
As it stands I have stopped doing Day Trader and ended up ignoring it for all of Emissary.