I guess some of the issue with this is due to the fact that it's one week and you can only react to it when the enemy has already advanced quite a bit, which makes one feel somewhat helpless.
Now imagine there would be a "stance" besides REFIT/RESERVE/READY, which you could put a Unit in ...GUARD is already used in game, SECurity is used, Garrison is used ...let's call it WATCH.
This WATCH stance would allow the Unit to reduce enemy movements either
- of the type "pending Hex->Enemy Hex" (excluding ZOC movements)
- or it would actually increase the ZOC of the WATCH units by 1 or 2 Hexes
...so it could just assert control over an area. The radius could be like 2-3 Hexes or so. How it reacts is the next question. Something like increasing MP spent for the enemy in this area (like +1MP if you have a Regiment/Brigade and +2MP per Hex if you have a Division in the new WATCH stance) would be an idea. If it would just be "increased range of ZOC" then normal ZOC rules could (mostly) be used.
The downside of WATCH could be to start next turn with 0MP (only being able to move a single Hex).
Putting a Unit into/out of WATCH could cost AP and both things could only be done when X Hexes away from an enemy in supply unit.
Bigger Soviet Corps Units could be excluded from being affected by this "area effect".
Or all units with X amount of CPP (or whatever) could be excluded from this effect.
And yes, I know it's unlikely the Devs would implement a whole new mechanic.
And yes, I know if probably could be cheese'd especially thinking about 1941 if Soviets would also be allowed to use the WATCH stance.
From what I see, if you'd make it Axis only and Exclude Corps units being affected, this would mean no chance to exploit it as Soviets and it would allow Soviets to still do proper advances with serious (Corps) units and it would lower the effect/reward of using "cheap" units for Suicide runs (with which TB units would deal initially/historically).