Much like in real life, to take a town you want a force that's a good 3x larger than the defenders.
In urban environment the ratio needs to be 9 to 1. In forest it is 3 to 1.
The difference is that in forest fights are only horizontal and ranges are short (depending terrain, but usually only 25-50 meter for infantry fighting) but in urban environment, combat happens in all axis, you can make attack from low (cellars) or from up (roofs) and single position can give defender a 270 degree view. One squad can hold a building and fight in all four sides same time.
When defender is in forest and has recon and attacker comes from open field but does not have recon, the situation is then realistic 3 to 1.
Example 4 IFV + 4 Jäger defending forest and there is assault where attacker has 3 MBT, 12 IFV, 12 Squads (motostrelki) and artillery support. Defender can cause over 90% losses to attacker while defender losses are 100%. But at that point, when attacker only has 2½ IFV left, they lost the fight because they can not defend the location anymore against re-attack from defender reinforcements or they can not continue fighting. That is the rule that 20% losses are acceptable so your units can continue fighting, either taking defensive positions or continue assault. If you lose more than 20%, the units can not anymore work as doctrine says and everything becomes much slower, weaker so enemy can take you down right after. And if defender does it well, they retreat from locations at specific point to secondary defensive location and attacker needs to attack again, this time much smaller firepower meaning the ratio is more to 2 to 1 or less than 3 to 1. And at that point, defender has no problems to wipe attacker from earth.
In urban combat the attacker is so underpowered and needs to come in much greater amount of firepower to flush defenders out. If there is just one squad, you really need a 2 MBT, 4-5 IFV and infantry platoon and possible mortar support.
Of course, other way what you can do is that you actually level down the whole area with artillery so there isn't a rock what has not turn over. But that is just terrible strategy because you end up in situation where civilians attack toward you.
The game recon system and cover system does not work as it suppose to work. Defender does not have luxury for correct cover or hiding. Attacker recon can too easily see in forests (even to towns).
With just 2-3 squads it is too easy to destroy 5-6 infantry from towns just by going carefully house by house and retreating littlebit before contact. It takes little more time but 1 to 2 ratio where attacker has less says game system does not work well.
Now if I play Pact I simply just order one or two rocket strikes to town and that's it. Like there would not been any kind cover at all.