If there is any gain in sensitivity after deploying the TA about 1/3 of the way, I haven't noticed it. That does't really bother me much, since that's still a long way from the boat and any interference it might be casuing. Don't forget that the LW/Ami TA's are substanially longer than the TA's in stock DW.
As for why not to deploy it all the way... reaction time. Sometimes you really want to start that other leg sooner, and having the TA in a turn makes it pretty useless. The sooner its back on track, the more data you get. The only reason I can think of why you'd want it longer is better triangulation if you get a second array on the contact.
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