I have a 2008 LHD SE comfortline that I bought in Germany as an ex-demo in late 2008. Up until mid 2018 it was my daily driver, and has covered, to date, 115k miles, mostly in Spain, where I moved to in early 2009 until returning to UK in mid 2015.
I run it at least once per month, (roughly 50-60 mile run) if not being used for its primary purpose, in an effort to keep it in good running order. Twice since being 'relegated' from my daily runner, it has had the EGR problem. On both occasions, my local garage has been able to remove and thoroughly clean the EGR and refit - a messy job (particularly, so I was told, the first time) and the problem goes away. Significantly, the second occurrence happened almost exactly 12 months after the first, during which the van had covered no more than 5,000 miles, so in my opinion it is related to usage (ie frequency of driving,) rather than miles driven, or perhaps the lack thereof!
Yesterday, on my monthly run, the dreaded loss of power associated with both the flashing glo-plug symbol and the engine management symbol happened again. This time, I adopted a slightly different approach: having switched off the ignition, and having both lights go out, I drove for 20-30 miles in 4th gear, with the cruise control set at just below 60mph. This gave ~ 2700 revs, and appeared to solve the issue, as I subsequently drove back home (approx 40 miles) after a break of 2-3 hours with no issue. As I have a DPF as well, I suspect that by cruising at higher revs for the extended period, I 'cleared out' the DPF in the process, which may be related.