Not every unit is infantry centric. So not every unit fits into that simplistic synopsis. Some units are vehicle mounted. Those mounts require maintenance. Stovepipes and empires have arisen to the point where drivers are not allowed to change light bulbs on SMP vehicles and units are not allowed to self recover, amongst other ludicrous impositions.
The loss of essential vehicles and equipment to national courses, and the resultant maintenance and return times, ensure that home units seldom get, and hold, their equipment long enough to properly train, whether at the soldier level or higher.
A simple example is a unit sending all its extremely serviceable MGs to summer training, having them returned in December, in condemned condition and told no replacements will be forth coming in the near future. Typically, they get replaced just in time to be sent for summer training again. The same goes for vehicles and radios.
The silver lining being the cumbersome, antiquated IBTS system taking soooooooo much time, there is seldom anything else to do.
Oh, and mandatory lectures, which have become absolutely comical in their sheer number.