Sorry, thats a little hard to understand.
I believe your asking why people run Talos and Cronos in units of 3?
There are multiple reasons to use large squads, always to maximize buffs or to overload in one profile.
Buffs that you would maximize are generally Torturers Craft (reroll all wounds in Combat), or Never Stationary (to jump a unit of Cronos over a wall, shoot, then fall back behind the wall out of Line of Sight).
People may bring large units of Talos because you can only take 3 units max, and with units of 3 you are able to fit 9 into your list.
It is also sometimes nice to string your units out, to try to block movement or try to get in range of a Haemonculus healing buff.
Please note that Cronos/Talos are Coven units, and cannot use Lightning Fast Reactions (-1 to hit) as a result.