A good 'rule of thumb' is that one calibre of seating depth,i.e .277 into the case mouth for 270 rounds,but,and this is a big BUT,most calibres larger than .224 won't be able to be seated this way because the bullets are simply too long for this.Case neck length differs from cartridge to cartridge,and this will change seating depths significantly.
If you are shooting a target/varmint calibre,the above rule will mostly work,and it does in the 22-250,22-250 AI,220 swift and others.
If it is a hunting rifle you're using,then the magazine length,throat length and length of the bullet will determine the seating depth.
The 25-06 is a very good example of throat length influencing the seating depth.This cartridge is chambered with so many different throat lengths,even in factory rifles,that there is no 'rule of thumb' for it.
You simply have to measure where the origin of the rifling touches the bullet in this case,and then back off .020"-.050",or closer,or further,to get the seating depth for EACH bullet style.Reloading manual quoted OAL figures may or may not work in any particular gun.
I recommend getting one of the bullet comparator tools or RCBS precision mic's,so you can get your bullets seated the correct distance from the origin of the lands.
Now,seating a bullet so far out of a case so that there is only a very small proportion of the bullet in the case,less than 10% of the length of that bullet,is a very bad idea,for these reasons,the bullet will begin to move at the first instance of the primer detonating,which can cause the bullet to tip because there is insufficient speed to make it 'jump' into the rifling,the neck tension will be so little that ignition in the case is poor,because the bullet being held tightly helps build the correct amount of pressure before the bullet moves in the neck,and lastly,you can end up with the S.E.E (secondary explosion effect) by the bullet jamming in the lands when the primer detotnates,and the rifle turning into a BOMB.