It depends on the model, some have lots of weight on the nose wheel and some don't. It's the friction and load that is a problem. If you switch on, fire up and go then great, but people phaff around with the model on the ground and the servo is loaded way more than a control surface. Like everything you can get away with a Digital sure, but some operators are not mechanically sympathetic! Closed loop steering that is over tight, tight ball links on direct rod type and even dry nose leg steering bearings all affect the servo- yes you can burn out an analog servo too. For sure battery use with a digital servo will be more per flight