ORIGINAL: tyronec
I take a different view.
What happened on T3 in the game is Axis were able to get around the back of Pskov. They did so by attacking the three Blue units and then advancing along the Red arrow.
That's why it is fool's gold. I'm happy to see a Russian player pile up counters on that river, I'm driving around and blasting their units on clear terrain where they don't stand a chance. Now I'm behind them and they have to move to get between me and Leningrad (if I didn't already pocket them in the leap), so I've strategically leveraged them off the river without firing a shot over it - and that's if they're smart. If they're not and they try to hold Pskov another week I'll bag the lot.
The point in defending the river line is not so much the defensive bonus from attackers crossing the river, it is the MP hit to Armor for moving across a river into a ZOC, but Axis were able to wreck the defence and clear the way for some units to get a good advance past the river line without any penalty.
That's great, if the Axis player is bullheaded enough to come right at your dug in river defenses.
But you shouldn't count on that against an experienced player. They're going to use the panzer's motor and find a different path.
There is a problem with what you suggest that the Soviets should have pulled back to rough terrain earlier. Pskov is a bottleneck with the lake guarding the right flank.
It isn't a bottleneck against a good player. It is a cauldron for Russian units to be pinned against that lake. Now you've lost map counters. Now you can't exert ZOC costs on every line of advance in depth and you grant the panzers operational freedom in what should be swamps and forests. You can't let those swamp and heavy woods hexes flip without extracting the MP cost of combat. The MP cost of bulling through the woods north of Pskov is much, much greater than the MP cost of breaching the Velikaya (if your opponent chose that worst course of action).
Once Soviets pull back then they have to defend against possible Axis lines of advance. The Green one is the best, most open terrain and the fastest route to Lenningrad. The Blue one has more heavy woods but protects the double rail line, it is certainly viable for Axis (and has been used in previous games) once they get some infantry up. The yellow one is not great but it still has to be defended and it is protecting the double rail line to Lenningrad just north of Novogorod. The Soviets just don't have enough units on T4 to defend all of these.
I hold the yellow line to be the best path of advance for the Germans because of the favorable terrain, the ability to cut supplies, and by going with the right hook most Soviet players will still feel compelled to hold the western approaches to Leningrad and thus spread themselves thinner and put many of their forces strategically out of position to contribute to the outcome.
For the Soviets to hold Lenningrad they need to be able to hold up the Axis Panzers at Pskov at least until the Axis infantry arrive. Otherwise Axis just get too far forwards too quickly and the defence is hopeless.
Russian has to fight from terrain that reduces their losses and the panzer combat power (swamps and heavy woods). Build plenty of depots to rotate the retreated/routed units onto so they can be used the following week and have combat power and not just be shells.
You have to screen the Velikaya and Sorot, but you can't try to hold them and you can't afford to give up any map counters so you can defend in depth and deny the panzers operational freedom and 'free' hex flipping against an experienced human. Since you can't really counter attack, you have to make the Germans player fight for their gains.
"War is never a technical problem only, and if in pursuing technical solutions you neglect the psychological and the political, then the best technical solutions will be worthless." - Hermann Balck