As others have said there are a lot of genetics involved to have a fitness level in the 4.5wgk level.
In addition ‘life’ is either an aid or block to ones ability to train resulting in increased fitness.
A few hours per week won’t elevate a rider to the elite or near elite level. A lot is talked about regarding zone 2, etc. but elite riders will ride ‘hours’ per ride when doing zone 2 work, not an hour or two.
Additionally ‘life stress’…ie work, family, sleep, etc. play a big roll in fitness.
IMO training for FTP only is not a good plan because your ftp fitness varies so much week to day and even day to day depending on wellness, fitness, etc. Training plans generally start at a base and build then rest…rinse and repeat…increasing difficulty as fitness increases so there really is no ‘steady’ increase but a series of peaks and plateaus though over time a steady increase in fitness…and ftp increase…results. The more fit you become the smaller/incremental the ftp increases become unlike new riders which often see a big increase because their base is so low that even a bit of training shows big increases.
My suggestion is to decide on the type of rider you are trying to become…ride for pleasure, fitness only, competition…LOL then decide what type of competition…grand fondo, fast group rides, perhaps a team, crits, TT’s, road races, etc. Some of these require a very different training plan…crit vs TT…and while your ftp may not show big increases your fitness, speed and durability is shown by fitness today vs a month or two ago or in the events participated in.
I’m 71, my current TR ftp is 218/3.1wkg…I’m 5’3” and 145lbs. I’m using the masters aggressive plan with two hard days per week and six training days…I typically ride 8-10 hours per week/6 days. This includes two days of weights at 30 minutes per day and two one hour yoga sessions weekly. I do race competitively, winter months on Zwift, and USAC/Local events during the ‘irl’ season. My TR ftp rises and falls depending on my weekly training schedule but I rate my fitness based on how the ‘hard day’ training feels and the results as well as the Zwift race results…I’ve been using TR only a few months, prior I used a personal coach…expensive…and my own training program based on feel and decades of training/racing. I find TR to be working well and most importantly keeping my training ‘in check’…I can easily overtrain and find my fitness declining because of this…using TR I get more/better recovery which results in better results during my ‘hard’ sessions and races.
Overall I’m satisfied but the season hasn’t started yet…I’ll know better after the 5-3 NY State Crit Champs…
Good luck and keep us posted…
accurate