InStocks is a great place to show off and prepare for TL. (Speaking from experience)
I agree
Even though Instocks may be a lower paygrade than backroom, if you are looking to stay with Target it is a great workcenter! You will learn a ton since Instocks has its hands in so many different areas and processes and as you get more comfortable you will be able to speak to more and more things going on in the store! I knew what Plano was doing, where Pricing had its largest markdowns, how the trucks went the night before, if backroom was keeping up with pulls, if the salesfloor was behind on salesplans, what transitions were coming up and where the most flexing needed done etc... Basically you HAD to pay attention to all these areas to do a good job! Its also a great workcenter because there are so many things you can "captain" for the process since most TLs are fine with a TM owning those things! Whether it was raincheck effectiveness, outs with locs, the drastic count report (partner with AP), the PTM process for a certain area... There are tons of things you can own and then speak to later in interviews!
I am a firm believer that you don't HAVE to be in any certain workcenter to show them you can be a TL... I have seen MMB Specialists, HRTMs, GSAs, and SLBTMs promote to TL easily too because of their ownership of an area! I just think ISTM is one of the few positions that allows you to showcase "collaborates" as a strength because of your ability to help out in so many areas!