Just making sure I understand your timeline - you have 3 surgery Sub-Is already scheduled for this summer (SICU, minimally invasive surgery, and gen surg). June, July, August?
When do you plan to take Step 2? Although Step 2 is typically easier to do better on that Step 1, it still takes a decent amount of dedicated prep work/study time. My Step 1 score was only average (not SDN average - real life average) and I studied for a solid 3 weeks (for Step 2). It paid off and my score (percentile wise) improved quite a bit. If you want your Step 2 score available when you apply, I'd recommend taking it early summer (June through mid July).
Depending on the flexibility of your 4th year schedule, I'd do something like this:
-June = Step 2 studying (take Step 2 three weeks into the month, then enjoy a week off to work on ERAS stuff and relax - you're going to appreciate that week when you're working at your max potential for 80+ hours a week during your Sub-Is)
-July = Surgery Sub-I #1
-August = Surgery Sub-I #2
-September = Surgery Sub-I #3
-October = Surgery Sub-I #4 (last Sub-I, as Nov/Dec will busy with interviews)
The purpose of your first two Sub-Is is to get LORs and face time with programs you're potentially interested in matching at. Get your letters in July/August. Make sure the Sub-Is you have scheduled those months are with people you want writing your letters (program directors/chairmen/senior faculty). Honestly, I'd just do two gen surg rotations during those months at different hospitals, or if you want to stay at the same place, do one gen surg rotation and another rotation that has A LOT of contact with the gen surg services/attendings (at my hospital, the SICU is run by the cardiothoracic surgery folk and the intesivists - the gen surg attendings (including surg onc/hepatobiliary, colorectal, endocrine, trauma) spend almost zero time there (their big belly surgery patients go to our trauma ICU) and gen surg residents spend little time there too - so not a great Sub-I for someone interested in the general surgery residency - possibly my program specific). Just make you're rotating with the RIGHT people during your rotations - just because it's a surgical rotation does NOT mean it'll benefit you in the application game.
The purpose of subsequent Sub-Is is to get some face time with programs you're interested in (the time to get LORs will have passed). Again, I recommend only doing rotations with the general surgery folk. As someone with a less than stellar application (not judging - mine was too and I successfully matched) you want programs to get to know you - and know that there's more to you than what they see on paper.
I'd scratch the CT and PRS rotations. I'd consider doing them during electives later in the year (once interview season is over) if you REALLY want some exposure to those fields. But honestly, after several months of Sub-Is/application and interview season/stress of the Match, you might want some cush rotations to finish out the year - just a suggestion...
Good luck!