Individual preferences and circumstances vary.
Coasting, braking, or paddles downhill may give some regen, and HV charge mode will not interfere with that.
It seems the ICE charging rate is all the battery can handle, so if there is regen occurring the ICE is not able to additionally charge the battery. The ICE 'waits' until the regen is done before charging the battery. The ICE may be on and off, depending on terrain and charge level. HV mode will use the ICE to recharge the battery to the HV starting charge. If this charge level is sufficient, there is no reason to use HV charge mode.
Individual preferences vary: I reset HV mode on long inclines to avoid high-revs on the ICE. Doing this for numerous inclines will cause the battery charge to decrease. HV mode will not use the ICE to bring the charge above the level that HV mode started at or was reset. HV charge mode can restore the charge up to 58%
In cold weather, I find keeping the battery at a lower charge will keep the ICE rpm's better controlled. When I start my inclines with this low charge level, I may have to use HV charge mode to get the charge to a comfortable level after an incline. I do not allow HV charge mode to go up to 57%, but just use it to bring up the baseline charge level.
Obviously, individual preferences vary, but I do not find switching modes a couple times in a 2-hour trip to be excessive, to maintain a quiet ride. I really enjoy the quiet ride of EV mode, and gear mode.