From D&D 3.5 to 5.0(5E) - 23 - Initiative Order Doesn't Change

Shuffling character initiative orders during combat is another victim of the rules simplifications in 5.0.  I am not sad to see it go, although it can allow a character to have back to back turns.

For example, if my fighter is in a narrow hallway behind my friend the monk, and the monk is fighting an orc, the combat could go like this:

Round 1:

1. Fighter "readies an action" to attack the orc if the orc drops the monk and steps forward.
2. Monk attacks the orc and hits two times for 10HP.
3. Orc attacks the monk and hits for 8HP knocking the monk unconscious. The orc steps into the monk's square.
4. Fighter uses his "readied action" to attack the orc and hits for 6HP.

Round 2:

1. Fighter uses his action to attack the orc and hits for 9HP.
2. Monk, rolls a death saving throw.
3. Orc attacks the Fighter and misses

In the above example, the fighter got to take two actions in a row.  That will happen occasionally, but most the time it will probably not occur.

The thing to remember for 5.0 is to leave the initiative order as it was in every round throughout the battle.