My primary exercises are walking and paddling SUP. I am going with 50 calories a mile for walking and 120 for paddling. Sometimes I swim and I am using the mfp entry for casual breast stroke and then editing it down a little. I will worry about more accuracy when I get into the low 150s. I am not sure I really need high accuracy. If I get toward the high end of the range, I will decrease my base and trend lower, if I get to the bottom, I will up my , base calorie goal. I don't think it will ever be "set it and forget it" but trending in one direction or the other is slow enough to give me plenty of time to respond.