I agree with the eq, if pure mass gains are wanted then I'd up test much higher but that's just me. About the slin the user should know how much he needs to eat from each dose. I prefer humulinR by the way. Knowing how the endocrine system and pancreas work, helps when it comes to being concerned about time on time off. The pancreas does not know if you inject insulin or not. All the pancreas does is release insulin when blood sugar gets high, and release glucagon when it gets low. Though normal secreted glucagon usually isn't fast acting enough to counter injected insulin. What I'm getting at is as long as the pancreas isn't permanently suppressed for long periods of time, there should be no concern. The pancreas releases insulin all day long every day in spurts. Generally more is released after meals. But it's constant, insulin is secreted even during sleep. As long as the pancreas naturally releases multiple times a day then there are no concerns. If hes only planning on doing 10iu per day that's hardly anything.
1. if the 10iu dose is split up then the body will continue to secrete MORE insulin even on top of it because the pancreas senses when blood sugar is high.
2. if the 10iu dose is all at once, then the pancreas is STILL not being suppressed because injected slin only lasts a few hours up to 8. There are 24 hours in a day so once a day isn't enough to suppress. Meaning you could inject 10iu once a day daily every single day for 3 years straight then quit dosing insulin and the pancreas will continue to release normally and it would resume and function completely perfect without any concerns.

50iu per day is equivalent to the average amount a normal healthy person secretes daily.
Insulin is a hormone yes, but there is no "suppression" because it gets released naturally all day long as long as blood glucose levels are high. Even if blood glucose levels remain low all day insulin is still secreted but in smaller amounts. The only way to completely shut down the pancreas of insulin secretion would to dose insulin in doses much over 40iu per day, BUT that needs to cover the full 24 hours or the pancreas will remain secreting insulin.

A bodybuilder could inject 120iu slin per day and as long as he does it and still leaves enough time in each day for the body to naturally secrete then the pancreas will not shut down.
In other words the 4 week gap is unnecessary. Its a myth/broscience that some steroid users made up because they thought the pancreas works like the pituitary. The pituitary will NOT release growth hormone when superhuman levels are present. It gets shutdown afterwards for a period of time because the hypothalmus told it to stop. The body is good at balancing out. Testosterone is the same, the pituitary will not release much testosterone at all if a user is injecting a gram a week for 12 weeks, the pituitary will take up to 12 OR MORE weeks to normalize. This is because it was shutdown all day long continually for months at a time. Also testosterone is not a life or death hormone, a person can live without a high level of testosterone.
A person will die or become very ill and destruct itself if insulin is not produced so the pancreas will not "shut down" this is because it is not controlled by the hypothalmus.

A person with type1 diabetes has an autoimmune disease and is completely unable to produce or secrete insulin. Type 2 diabetes is able to produce insulin but either A. not enough is produced, or B. insulin receptors are nonresponsive to insulin protein. If there is anything to be concerned about it's insulin resistance. So that is really the main thing to watch out for. 10iu (even if he injected it daily nonstop for a year) isn't enough to cause resistance because the body produces much more than that naturally, so receptors will accept the ligands without even knowing you injected. Of course a person injecting 100iu a day needs to be more careful as to not develop insulin resistance. Also a person who is using enough insulin that it covers most of the 24 hour day continuously, needs to watch out as well.