If you're brand new to CE or athletics in general, you probably haven't given this much thought. Training for CE is a big commitment and is a long term investment (some times 8+ years of training). It is important that the day-to-day is consistent and agreeable to you. By that, you agree with the principles of training of the coach/group, you share a common purpose, are supportive and you share the same values.
For me personally, prioritizing progress through learning, developing and progressing correct movement patterns and viewing every athlete's unique background as the starting point for planning their training is paramount.
"Appropriate challenge drives optimal development"
Finding a club is easy, finding a good venue is more challenging and finding a coach that you want to train with is the rarest of all. If you are committed to progressing as a combined event athlete and live in the South East of London/Kent/North East of Surrey, I'd love to hear from you! But more than likely you aren't.
There is the argument of multiple coaches vs. solo coaching in CE. Having had 52 coaches over 25 years myself and having had anywhere from 1 to 8 coaches at any one time, I can tell from experience that it isn't optimal to have multiple coaches. If all of those coaches are working together, have regular meetings, are discussing progress and are all working from the same plan then that still isn't as optimal as just one coach being able to give immediate feedback and having an instant sense of the "bigger picture". Especially for young athletes where movement skill acquisition is paramount, having conflicting messages/philosophies/focus points is no good.
However, a single coach would need to be experienced, dedicate a lot of time (which a lot of amateur coaches can't do) and be committed. It makes sense from a time/resource management point of view to divide the "labour" up in this way. However, historically in the UK, our top Decathletes have not achieved results in this manner.
If you're new to the sport, it's difficult to tell how committed you are going to be for a long term project like CE training. If you're young and developing, your body may adapt and grow differently and CE may be something you may not want to do anymore. It is also down to personal circumstance i.e. it is convenient to train after school but what about when the athlete is older and after work? When they have other commitments like a family of their own? University/College? Shift work?
It is possible to train effectively for combined events if you can plan accordingly due to your circumstance. However, many athletes fail to realise just how big a commitment training is and end up dropping out of the sport. Some athletes come into combined events at a later date (e.g. at 17/18 after having played other sports or only having done a couple of events before). A classic example is double Olympic champion Daley Thompson having trained as a sprinter while growing up and starting to do decathlons in his late teens.
From this section onwards, I am going to be talking about training athletes from a young-ish age (11/12) and taking them through the senior ranks (28-30).