A hose that is soft is on its way out.

Trouble is, that is a one way test. A soft hose should be replaced, but one that appears fine may go just as quickly.

If you have a slow coolant leak, it is worth tracking it down as it is likely to get worse, not better. Do it at a time and place you choose.

Those that are replacing all hoses and the expansion tank as a preventative maintenance step aren't really doing it because of the hose, per se. It is the same work to do it before or after failure. They are doing it because after a hose goes, if you don't pay attention and know about the potentially expensive consequences of overheating a BMW engine, you can be in for $$$. I haven't replaced my hoses or expansion tank based on time. But I also know that if I run out of coolant, I won't be driving it to the next town to get it fixed the next day. I will be pulling over because I don't want to worry about a warped cylinder head.

__________________
2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue