Seeing as the DMG is pretty explicit that the average party should only be running out of long rest resources after an 'adventuring day' of 6-8 medium-hard encounters, and are expected to have 2-3 Short rests in that time, 2-3 encounter adventuring days should be pretty rare.
How many dungeons do you know that only have 2-3 encounters in them? You wouldnt even be 1/3 of the way through most dungeons at the 2-3 encounter mark.
So if I understand correctly, you enter an area that has connected rooms. First room has you roll initiative. You cast some long lasting buff and try to keep it up for 10 rounds as you move from one room to another. Once 10 rounds are up you are likely to have gone through 2-3 "encounters". Unless your DM allows your Hex to be kept in stasis or applied to a chicken that follows you around, then when you move from one room(encounter) to the next room (encounter) you must either drop concentration in favor of some other spell or eat the loss of optimal DPR. You are likely to then take a short rest before smashing out 2-3 other rooms(encounters). Thus you've had 6-8 "encounters" yet only had 2-3 short rests. Do I have it right? I've never played 5e, so campaign norms are foreign to me.