There's a bit divide in most directional drilling firms between the DDs and the L/MWD hands, although things are changiingn slowly...on the project I've just finished we had to get some cross trained DD/MWD guys (bed space was at a premium on the particular platform) amd there was a bit of resistance from the service crews. DD used to be drillers first who then moved into directional work (and they all seemed to be from the Cariibean for some reason!)
Your work pattern will depend upon where you are and so on. From my time with Schlumberger, unless the location is a real toilet, SLB will post you somewhere permanently and you'll then work equal time(ish), depending upon the amount of work at the location. Right now in the North Sea, everbody is so busy that guys are going form one job to another with almost no time off. There are stories of people being shunted over to work in Norway for their 1 week off every 3 weeks that is required by UK law, and then coming back to the UK sector to do another 21 days having had a week 'off'! However, as the rig bonuses are such a large chunk of their pay, no-one's complaining too much, apart form guys like me, who have to deal with a DD so knackered that some of the decisions may be a bit dubious...welcome to the oil patch!