one thing to remember, you don't have to 'stick it' at the very start. You just wait until it is 2/3 done, then take a temp reading. Based on that reading, judge how much time until your next. So if your desired temp is 160° and it is 120° now, you should wait probably 45 min to an hour and test it again. If it is 145° then you know it raised 25° in an hour and you should wait maybe 30 min. until your next stick. Don't leave it in there, your display will get cloudy; after repeated uses it will be impossible to read, regardless of cleaning. Always pick a different spot or spots. Keep track of your progress with good records. Then you build a history and very soon you will stick it once and next time it will be perfect; it is a learning experience. I did two 3 lb. chickens and an 28 lb turkey (cured and smoked, about 8 hours cook time) at the same time:
I assumed the chickens would get done far faster than the turkey. Wrong! They both worked up to temp at the same time; the turkey getting pulled only ½ hr after the chickens, believe it or not! And, as you can see, no probes in them; I took readings like I said before until the last 10°, then leaving the probe inside it. It was a great learning experience for me, just that one smoke!
Again, keep good records! Start a Smoke Book and record your smokes, anywhere from very simple to very complex. It is INVALUABLE data! It makes it almost hard to do a bad smoke (but remember, identical pieces of meat can take different times). Plus, you will be able to 'dial in' your smokes to know about how long it will take after a few tries; your wife will appreciate your efforts to keep records so she can know "what time will dinner be ready?" - you can give her that time quickly with good records and preplan your smoke!