The favored method (by professional troops) is the silent (night) attack where you move to the start line silently (possibly with diversionary fire) and your fire support commences to neutralize selected targets as soon as you break cover. It is both planned fire (before battle) and directed fire (during battle) - it doesn't roll but it can be switched back and forth by your controllers. Rolling barrages are better referred to as creeping; the arty like to push them forward and then bring them back to sweep the same ground several times and let the infantry catch up. The problem is this is extremely wasteful of ammunition - much better to have real targets. The only creeping barrage I worked under was from mortars and that was to lay a mix of HE and smoke. We also used to use our medium machine guns with a different colored tracer for each company to indicate our lines of advance to specific enemy positions when they would switch to the next position or "tactical bound".

Q-37 and Q-36 balistic radars are deployed with all FA units at both battery and brigade level in US ARMY. Modern arty is about shoot and scoot. That is why MLRS becomes so valuble. An M270A1 launcher can lay (aim), fire a 6 rocket barrange, and stow in less than 60 seconds. Any unit that sits at a fire point for more than 60 seconds risks counterfire. The combination of dedicated counterfire units, tag radar, and all digital C3 systems means that counterfire comes rapidly and is very accurate.

You are correct about artillery radars making long barrages dangerous against an enemy with this capability. However, ignoring that risk, a ground commander has a lot of flexibility with planned fires on an objective. A simple and effective way to keep the enemy suppressed as you approach is called "echelonment of fires." Simply put, you fire your biggest asset until you reach the point where the risk to friendlies is too great, whereupon you "turn on" the next smallest asset and "turn off" the heavier. This enables you to get very close to the enemy before he is out from under indirect attack, as close as 100m if you have 60mm mortars available. Naturally, all of this is contingent on ammunition supply and availability of assets. A good guideline for the minimum safe distances: 1000m for air, 750m for naval gunfire, 400m for 155mm artillery and 120mm mortars, 300m for 105mm arty, 200m for 81mm mortars, and 100m for 60mm mortars. The numbers are subject to the maneuver commander's preference, but they're in that ballpark.

The fact that we (the world in general) are progressing rapidly in the areas of precision guided shells and effective cluter munitions, it could easily be argued that within the next few decades or half century that massed barrages become obsolete for all except third-world and rebel contigents trying to harass their enemies. PGMs and course corrected cluster shells to defeat personnel and vehicles can be deployed in less numbers than standard HE rounds, and can be far more effective. There is the cost issue, (an estimate here, not solid figures) because if half a dozen clusters shells or PGM rounds can effectively neutralize an area as opposed to a dozen or more standard rounds, that may be preferred. And it could also improve the field life of gun barrels if they are firing less numbers of rounds each engagement to effectively eliminate targets. Considering that many of the newer artillery systems can do multiple round simultaneous impact on a target, and at ranges of up to 40km and greater, "shoot and scoot" will most likely be the favored method, just to avoid such effective counter-battery fire which can reach targets up to 30 or 40km distant within 5 minutes (with an alert FDC/FireFinder crew). Will we see the end of the fixed emplacement towed artillery and ground mortar systems in favor off all-SP versions? Probably not, but a legitimate arguement is there..