Elk are social creatures and they are curious. They will respond to calls, but generally more subtly. It isn't abnormal to get a bull to bugle even this time of year, but they won't repeat themselves very often, so it is a good locator strategy to find the general area where one is. Cows will chat a little too. If your going to call, set up on sign or in an area you know they are about, set yourself down with the wind in mind relative to where you think they may approach, and subtly call. Use a cow/calf call and occasionally give a gentle call. A couple of different calls mixed up may give the illusion of a small group. They will generally come in quietly and you may be surprised how close an animal that large can sneak in on you, even in the driest conditions. Approach it a bit like predator calling, keep your movement to an absolute minimum, set up so it is difficult for them to approach from a direction where the currents will betray you, and be patient. It is probably similar (though this is based on what I've read, not personal experience) like calling lions. Plan on keeping your butt still for an hour or more before giving up. I've not used decoys, but expect they may really shine in a set up and call situation.
Many have had success setting on wallows. I don't much have the patience to do either. Don't under estimate the benefits of glassing at first light. They will move into cover, but if you can spot them, at least you have a starting point. Still hunting can be effective, but you must work the timber VERY slowly, pay attention to the air currents, and again you will benefit by glassing every few feet. You will be looking for small indicators of body parts: a lower leg, the twitch of an ear, a portion of a tine... Remember that while you may come across the odd lone bull, there are greater odds of finding them in pairs or small groups. I.e., if you spot one in the timber, you'd best know if or where the rest of the group is as well. It isn't uncommon for me to work my way through the timber only to have a group explode out of their beds all around me.
Excepting for sitting on wallows, all of the above have gotten me many close encounters with elk. That being said, I've harvested few beyond the glassing and spotting method. I hunt sunup to sundown with the odd short nap thrown in and find I have more opportunities to spot and stalk than anything when they aren't assertively coming into a call. Elk bed during the day. They also get up and browse, get a drink, and otherwise move around. In 25+ years of hunting elk, I can say I've seen at least as many during the "non productive" times of day as I have early morning and late evening.