Look at the only Israeli designed MBT (Merkava) to get a little insight into how their military is structured. Small unit tactics and training, they are exceptional. Intel gathering and FFF (find, fix, finish), they are exceptional.
If you expand that out to "big army", see my Merkava example - it is all predicated on the defense of their land. The Iron Dome - a defensive system. The Merkava, a defensive-minded tank designed with the engine in the front and a fixed cannon for static, defensive scenarios. They enact their defenses much like the Americans did in the battle of the bulge. Quick transitions of firepower moved along multiple axis' to coordinate and maneuver firepower as needed. This draws from past experiences of fighting a defensive war on multiple fronts. After taking advantage of gains, they did take the Sinai Peninsula. The point being they are not designed for sustained, offensive invasion-style attacks over such a significant amount of land & time.
The second they tried this, the biggest fear would be attacks from the rear from the usual suspects that they defend against today.