I don't think there is anything wrong with what the poster is intending. We did the very same thing for years in a combined power (31.1) process (31.3) vessel (Section VIII) shop. He posted it as a question for B31.3 which generally means more standard wall stuff. Bridge tacking is especially useful on heavy walls, where you can lay on some wazoo tacks and never touch the J or C-Bore, for example, but can be unproductive for thinner walls, which are predominantly V's, if you have guys that are capable of decent tacks. Especially using bar stock as opposed to bridging with say GMAW short circuit, another good method of bridging.
The question is, are the guys capable? And if they aren't qualified you have to completely remove the tacks.
We had some dayum fine tackers in our shop, and a quick visual by the welders in the ID would alert them if they had some issue of concern.
Another thing is, and I've posted this in here before, there is no point in running GTAW at say 9:00, or generally what is considered uphill. If they roll over the top and essentially run the root downhill (make sure your qual your guys for that if you go beyond 15deg) you can crank up the heat to 190 to as much as 225 (a technique that to my knowledge was initiated by nuke welders in a couple of Salt Lake area power shops about 30 years ago), and when you run across the tacks you can completely burn through them oscillating a little wider and then the welder doesn't need to worry.
We had guys in our shop do this very method and maintain less than 1% reject rates.
And with practice, when you look on the ID of the root you cannot even tell where the tack was. The advantage here is the welder can light up on a pipe and run the whole root without stopping, as opposed to having to stop and grind out bridges.