Ok, I have read that thread, but I don't see how adding chin-ups between sets would be a "very very bad idea". I am very proficient at chins so I doubt 100-odd reps a week would negatively effect my training. Can you explain why it is a bad idea?
1. I am assuming you have not run Sheiko before (or not for a long time). You might be good at chins but most people are shocked, at least initially, about the amount of volume in a Sheiko cycle. Adding in another 150 reps a week would likely make this worse IMO. No matter how good you are at them I think it would affect your DL (you will probably be doing more pulling than you are used to anyway) and your overall recovery. You will already be likely be in the gym for 2-3 hrs a time so adding in another half hr for chins would increase this further and eat into restoration.
2. You already have available slots for SPP and GPP work. Lots of them, so there’s no need to add in more. GMs, RDLs, DB Press, Incline Press etc. are examples of SPP exercises that could be chosen. Similarly, Flyes, Triceps, Biceps etc. are all examples of GPP excersises that could be chosen in these slots. Sheiko has said that each athlete should select exercises in these slots which are appropriate to their needs. Search something like “SPP list” on this forum for a post containing the different SPP / GPP exercises listed in Sheikos book. They give examples, but you have plenty available spaces to choose upper back stuff if you need it.
3. This is the main one….there is a ton of benching in all the Sheiko cycles. You need to balance this degree of internal shoulder rotation with external shoulder rotation exercises. People sometimes over-simplify this IMHO and think “press = internal rotation, back work = external rotation” but it aint always the case. Flare your lats…what happens? Shoulders rotate inwards. For the most part, chins develop internal rotation of the shoulders. I am someone with pretty fruity shoulders who does need to include a lot of external rotation work but chins is not the way to go IMHO, these will only make you worse. Chest supported rows, T-bar rows, seated rows, DB rows etc. are better choices, i.e. horizontal pulls which involve retraction/depression of the scapulae.
4. For an example, here is how I set my GPP / SPP choices. These are obviously unique to my needs but you should be able to see how I balance out internal/external rotation for my bad shoulders (I run a 4-day CMS cycle):
Day 1
DL/Bench/DL
SPP slot 1 (DB rows)
GPP slot 1 (YTI exercise, rvs flyes & external rotations)
SPP slot 2 (DB press)
GPP slot 2 (abs)
Day 2
Bench/Sq/Bench
GPP slot 1 (YTI exercise, rvs flyes & external rotations)
SPP slot 1 (GHR)
GPP slot 2 (abs)
Day 3
DL/Bench/DL
GPP slot 1 (YTI exercise, rvs flyes & external rotations)
SPP slot 1 (chest supported rows)
SPP slot 2 (DB press)
GPP slot 2 (abs)
Day 4
Sq/Bench/Sq
GPP slot 1 (YTI exercise, rvs flyes & external rotations)
SPP slot 1 (GMs)
GPP slot 2 (abs)
Hope this helps