I might be way to sleepy to understand the problem, i assume you have a directory full of log files and every so often a new one is made.

"ls -ctr PATTERN" should list the contents

-t sort by modification time
-r reverse order while sorting
-c just one column

so if the files where

mon.txt
thu.txt
tues.txt
wed.txt

ls -ctr *.txt would list them

mon.txt
tues.txt
wed.txt
thu.txt

the tail -1 just lists the last file (the newly modifed one)

so "cat `ls -ctr *.txt | tail -1`" gives cat the newest modified file.

if the issue is that you want some sexy 'look busy' dedicated window that always has the tail -f LATESTFILE going. yeah some sort of loop would be needed or a sexy tail. I dont know the tail command you have but ...

#
# this will try and get a PID from something and when that PID dies it will
# 'untail', then re-tail
#
while true; do
PID=`cat /var/run/TWSMERGINGTHING.pid`
tail --pid=$PID --follow `ls -ctr *_TWSMERGE.log | tail -1`
sleep 5
done

#
# this will keep tailing until the file goes sour (100 attempts looking
# at it with the no changes) and then it will get a new one
#
while true; do
tail --max-unchanged-stats=100 --follow `ls -ctr *_TWSMERGE.log | tail -1`
sleep 5
done

if you have a 'runfor' like command then obviously you could do that for "runfor 3600 tail ..." and it would run it for an hour and then retail every hour.

now for sleep