I wear ear muffs that come on the Peltor, Stihl or Rockman forestry helmets or I wear the radio muffs when cutting firewood in a yard or something relatively safe.
That said, I find that when heavy equipment is around or I need to hear where my guys are at or something else is going on I like the speed and therefore the "safety" of being able to quickly remove the muff and hear everything and then quickly replace the muff for when the noise starts again, without the time delay of waiting to squish some little foam thing with either my dirty bare hands or my gloved hand.
I worked with a guy that wore foam ear plugs and I always wanted to add up the minutes he spent taking ear plugs in and out, loosing them, finding them, going to get another pair, buying them, unwrapping them, cutting strings, tell me to hold on while he put his plugs in and so forth, in a days time, not to mention the incredible gross-ness of what his foam earplugs looked like after about mid morning, LOL.
To those that wear both plugs and muffs, I just attended a forestry class where two examples were provided of that setup likely causing or contributing to death. In both cases fellow workers were yelling at the guys wearing both to move or run and they could not hear them. One or the other will provide enough protection to prevent hearing loss, without causing you to not hear anything, no need to double up on it.
Sam