There is a myriad of of situations I have had that birds do not respond to me...
Last season, I watched a lone tom casually walking a ridge above me silently... I called at him, and there was zero indication that he reacted at all to my calling? Lone bird mid-morning? I concluded he was deaf... Or... Had seen me (probably previously came in quietly without my knowing).
The areas I hunt early season, the hens tend to stay with the toms all day... Often the toms will gobble back at me, and stay put or move further way (cause the hens they are with draw them further away). My two most common strategies early in the season, are to try to upset a hen (and draw her in with the toms in tow)... Or to gobble and make a ruckus that draws the attention and curiosity of the "flock." While both strategies have worked, mostly what I do with early season henned up toms is get frustrated.
Later in the season, when the hens typically leave toms about mid-morning... I'll pay attention to where birds are early, and hopefully what direction they are going, and plan hunt hitting those birds up later in the morning.
Early or late in the season, and hunting some of the hilly (and often steep) country I do... I will often try to get around, and in front of the birds (as I find it is tougher to call a bird back from whence it came than forward), and I will generally try to get above them if possible (as I have found it easier to call them uphill than down).
Also... A lot depends on the property I am hunting... Small property, I am more apt to sit in a strategic location, and do periodic subtle calling... Larger property, I am more apt to cover some ground and find a bird that is more apt to be more responsive.