What you are describing may be a mix of buss and star wiring, no way to tell how that will work. IF each modual is connected to a TIU output by itself, this is fine.
Putting 2 moduals on a output together is a mixed topology.
If you need 2 moduals on one TIU output, I would put the terminal blocks near the TIU output. Run a pair of wires from each module block all the way to the terminal blocks for star wiring. Done this way with a Rel L TIU you should have no issues. with an older TIU you may need lights or filters at dead ends and occasionally elsewhere.
As I mentioned, clubs have had success with buss wiring, using Susan's engineered filters at each power drop to the track and making each module a block. The filters keep the signals from crossing back into each other on the buss. This needs a lot less wire and is far easier to wire up in a modular layout.
The Reason for star wiring:
If you did not have blocks the signals on the track would keep going around as they gradually got weaker and collide with each other. it makes for a mess of jumbled signals crossing.
The details:
The signal is a series of square wave DC pulses, very short duration and fast.
When it hits the terminal block it clones itself onto each wire out.
Now, as the signal travels down wire and track, it loses strength. More so on track than wire. Keep this in mind.
The clones run down the wire into the track where they again clone and go both ways down the track. Now you have possibly dozens of slightly weaker signal clones running down the track. When they hit the end of the track they bounce ! Weaker but still running they go back, now eventually they reach the point they came in on the wire so they send another clone back down the wire and continue down the track.
Eventually they cross paths with the signal that went down that way and bounced back. Here is the problem. They are pulses in a chain, some gaps are longer than others, this is normal, but where they cross they may one or the other or both be high at any given time. This makes the signal unreadable there. It's a mix of 2 mirrored signals, not usually in time with each other. To add to the mess, the TIU may send the command several times, so you can have lots of copies crossing one another all over.
The one coming from the TIU will always be stronger, but enough copies piling up will make it unreadable. All this is why we make blocks with only one power feed per block. It means fewer signals are running around on each track.
The point of all this is the Filter will stop the signals that are weak from passing on, thus making only the original strong signal get around.
Optimal placement of the filters is at the end of the track at a block break, one on each side. These stop the bounce of the signal and you only have the original strong signal on the track, no echos.
It actually will work with one at each power input to the track.
This way you are only preventing echos from going back onto the buss and making it a mess by ganging up with others. (Remember that clone the signal sent back down the wire after it bounced?)
Top all this off with the reply the engine sends when it gets a command, if that reply doesn't get through you get CHECK TRACK, so it's important for the signal not to be bouncing back to the TIU too much.
I hope this does not confuse you even more as it is long and detailed.
email me if you need more info or help.
