I encouraged my students to keep a separate log book for blocks times, although I didn't do it myself. I knew one RAF pilot who kept a separate logbook for a long career and his hours were considerably greater. Ironicly, he never left to join an airline!
LASORs allows factoring, but remember that this only works for British operators. I work for an overseas airline who don't recognise notional taxying time. It can make a difference, I bumped up my total about 400 hours on leaving through the allowance, just short of 10%. But this is probably nothing like the actual time spent taxying. Some international airports keep you on the ground for ages. One short sector I flew regularly on leaving the RAF, frequently had us logging more time on the ground than the air! And when it comes to getting jobs and commands, ex military pilots at a definate disadvantage compared to their civilian counterparts.