From a game play perspective:- Since initiative is random it is unconnected from anyone else's roll. So you can roll initiative for each monster before the game. Also the grouping of character initiatives depends on the size of the party. If a party has 5 characters there is only 5 "gaps" for NPC to fit in. So its convenient to make this the maximum number of groups and bundle your pregenerated rolls together to suit. In practice you can just create a list of 30 initiative numbers in a random order. Start somewhere on the list (roll a d20 for the start row) and just write the monsters in each row. When you get to row 30 you just continue on row 1. If a monster is likely to be encountered more than once then on the prepared sheet have a couple of columns of different random initiatives. So the 1st column is combat 1, second is combat 2 etc. If you monsters are of mixed type it shouldn't matter if you do 5 orcs followed by 5 cobolds or alternate them, or any other sequence. You can then order them by initiative and divide them into a manageable number of monster "batches" if you want. That method is up to you but 5 batches could simply be all those with initiative 1 to 4, those 5 to 8, 9 to 12, 13 to 16, 17 to 20. Then take the highest initiative in each group as the position in the turn order. Then if the batches are called A,B,C,D,E you just create entries in the tracker for those groups with their initiatives Note that each token has a unique name so you can use the row number from the sheet in the name. This also prevents players knowing exactly how many may be about. Also include the batch letter so you know where it is in the order. e.g Orc15A This seems complicated but its basically saying you can do the initiative before play and get yourself organized.
