Without more information, this article is meaningless propaganda.
How many rounds are they designed to fire before they require maintenance?
How many rounds did they fire before they required maintenance?
How long are they designed to be down for maintenance?
Are they down longer than they are designed to be down, and if so, why?
A typical 155mm howitzer barrel is designed to last 1500 Equivalent Full Charge (EFC) rounds. That is 1500 rounds fired at nearly maximum range. If firing at less than max range, you might only have 0.7 EFC rounds per shot. If firing some rounds such as Excalibur or extended range HE, you may see 1.2 EFC rounds per shot. If these guys are firing 100 to 150 rounds per day, it stands to reason that tubes need to be replaced every 1 to 2 months, or accuracy suffers. It’s an artillery war, so you have to do the barrel changes. Every army has the same problem.